The importance of prayers is acknowledged by both the Shī’a and Sunnīs, who consider it to be one of the major pillars of Islam. One issue that has always been discussed by all major Shī’ī jurists was praying in congregation behind a Sunnī Imām. As such, this post goes through the opinions of different Shī’ī jurists from as far back possible to contemporary times, in order to get a clearer picture of the matter. What will become apparent is that the opinion on this matter remained pretty consistent amongst the jurists up until the 20th century, with only a few minor differences.
Before we begin looking at the opinions of the jurists, it behooves to cite a handful of relevant narrations that will assist us in understanding some of the verdicts given by jurists. The list of narrations is not exhaustive, and there are many more narrations that can be cited to convey the point being made in the traditions that follow:
قَالَ: وَ سَأَلْتُهُ أَنَ لِي جِيرَاناً بَعْضُهُمْ يَعْرِفُ هَذَا الْأَمْرَ وَ بَعْضُهُمْ لَا يَعْرِفُ وَ قَدْ سَأَلُونِي أُؤَذِّنُ لَهُمْ وَ أُصَلِّي بِهِمْ فَخِفْتُ أَنْ لَا يَكُونَ ذَلِكَ مُوَسَّعاً لِي فَقَالَ أَذِّنْ لَهُمْ وَ صَلِّ بِهِمْ وَ تَحَرَّ الْأَوْقَات
Jābir al-Ju’fī said: I told him (al-Bāqir) that I have neighbours, some of whom know about this affair, while some of them don’t. They ask me to recite the call to prayers for them and expect me to pray with them, but I am afraid that it may not be feasible for me. So, he (a) responded: Recite the call to prayers for them, lead them in it, and find the times to do so.
عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنِ ابْنِ أَبِي عُمَيْرٍ عَنْ حَمَّادٍ عَنِ الْحَلَبِيِّ عَنْ أَبِي عَبْدِ اللَّهِ ع قَالَ: مَنْ صَلَّى مَعَهُمْ فِي الصَّفِ الْأَوَّلِ كَانَ كَمَنْ صَلَّى خَلْفَ رَسُولِ اللَّهِ ص
‘Alī bin Ibrāhīm from his father, from Ibn Abī ‘Umayr from Ḥammād from al-Ḥalabī from Abī ‘Abdillah (a) who said: Whoever prays behind them in the first row, is like the one who prayed behind the Messenger of Allah (p).
وَ قَالَ الصَّادِقُ ع إِذَا صَلَّيْتَ مَعَهُمْ غُفِرَ لَكَ بِعَدَدِ مَنْ خَالَفَك
Imām al-Ṣādiq (a) said: If you pray alongside them, an amount will be forgiven for you that equals the number of people who oppose you.
وَ صَلَّى حَسَنٌ وَ حُسَيْنٌ وَرَاءَ مَرْوَانَ وَ نَحْنُ نُصَلِّي مَعَهُم
Imām al-Kāẓim (a) to his brother ‘Alī bin Ja’far: And Ḥasan and Ḥusayn would pray behind Marwān (bin al-Ḥakam) and we pray behind them (as well).
In the aforementioned traditions, we find the Imāms encouraging some of their companions to pray alongside those who were not considered Imāmī Shī’a. In other words, such individuals would be considered Sunnīs – who make up the majority of the Muslims today – though the technical term Sunnī had not been coined during that period. It is outside the scope of our post to discuss the opinions of the scholars on each and every one of these narrations, or their chains, and the extensive procedures through which they deduced their laws. However, as will be seen in their rulings, many of them have accepted the general understanding of these traditions and have even made references to them in their discussions.
Rulings of the Jurists
In our attempt to understand the opinion of the jurists, we will trace their opinions as far back as possible. The opinions of scholars will be presented in chronological order of their death dates, and will conclude with the opinions of a number of contemporary jurists. The scholars have further been segmented into different time eras, and the criterion to differentiate one phase from another is when significant changes in the methodology of jurisprudence took place due to a single or a group of scholars, or when certain socio-political dynamics caused the most popular seminary of its time to geographically shift to another location.
The first phase is defined as the era of the classical scholars, which initiates during the Minor Occultation, and ends around the beginning of sixth-century hijrī. The second phase begins with Ibn Idrīs al-Ḥilli who is famously known to have critiqued the methodology of Shaykh al-Ṭūṣī, that persisted within the seminaries for around two centuries. The former is credited for ending this stagnant period within Shi’ī jurisprudence. The third phase is marked by the formation of the Safavid dynasty that ruled over much of modern Iran. Under this dynasty, Shī’īsm was deemed the state religion of Iran, and was thus an important time as numerous scholars flourished under this period, and many were invited from other areas, such as Lebanon, to come and reside under the dynasty.
The fourth phase lists out post-Safavid scholars, and was an era of heated academic disputes between the Akhbārī and Uṣūlī schools of though. With the Uṣūlīs triumphing over the Akhbārīs, this era is also seen as an important phase for the development of Shī’ī jurisprudence, whose effects can be witnessed until today. Finally, a number of contemporary scholars’ opinions will be cited, as they remain relevant for all Shī’a Muslims around the world today.
There is no doubt that the list of post-Safavid scholars could have further been scrutinized and categorized from the perspective of scholars who were credited for originating their own unique methodologies for deduction. For example, scholars like Ṣāḥib al-Jawāhir, Shaykh al-Anṣārī, Sayyid Khū’ī and Imām Khomeini – to name a few – are known to have produced distinct methodologies for deducing law which made them stand out amongst others. To this effect, books as well as research papers have been written regarding their legal school of thoughts. While such categorization would be beneficial in understanding how different scholars and their students arrived at certain conclusions, such an in-depth investigation would be outside the scope of the purpose of this paper.
Classical Scholars (300 – 500 AH)
The earliest scholar we find discussing this matter is Shaykh al-Ṣadūq (d. 381 AH). In his magnum opus Man Lā Yaḥḍuruhu al-Faqīh, he refers to a treatise his father ‘Alī bin al-Ḥusayn Bābūwayh al-Qumi (d. 327 AH) wrote for him as follows:
وَ قَالَ أَبِي رَضِيَ اللَّهُ عَنْهُ فِي رِسَالَتِهِ إِلَيَّ لَا تُصَلِّ خَلْفَ أَحَدٍ إِلَّا خَلْفَ رَجُلَيْنِ أَحَدُهُمَا مَنْ تَثِقُ بِدِينِهِ وَ وَرَعِهِ وَ آخَرُ تَتَّقِي سَيْفَهُ وَ سَطْوَتَهُ وَ شَنَاعَتَهُ عَلَى الدِّينِ وَ صَلِّ خَلْفَهُ عَلَى سَبِيلِ التَّقِيَّةِ وَ الْمُدَارَاةِ وَ أَذِّنْ لِنَفْسِكَ وَ أَقِمْ وَ اقْرَأْ لَهَا غَيْرَ مُؤْتَمٍّ بِهِ فَإِنْ فَرَغْتَ مِنْ قِرَاءَةِ السُّورَةِ قَبْلَهُ فَأَبْقِ مِنْهَا آيَةً وَ مَجِّدِ اللَّهَ عَزَّ وَ جَلَّ فَإِذَا رَكَعَ الْإِمَامُ فَاقْرَأِ الْآيَةَ وَ ارْكَعْ بِهَا فَإِنْ لَمْ تَلْحَقِ الْقِرَاءَةَ وَ خَشِيتَ أَنْ يَرْكَعَ فَقُلْ مَا حَذَفَهُ الْإِمَامُ مِنَ الْأَذَانِ وَ الْإِقَامَةِ وَ ارْكَعْ وَ إِنْ كُنْتَ فِي صَلَاةٍ نَافِلَةٍ وَ أُقِيمَتِ الصَّلَاةُ فَاقْطَعْهَا وَ صَلِّ الْفَرِيضَةَ وَ إِنْ كُنْتَ فِي الْفَرِيضَةِ فَلَا تَقْطَعْهَا وَ اجْعَلْهَا نَافِلَةً وَ سَلِّمْ فِي الرَّكْعَتَيْنِ ثُمَّ صَلِّ مَعَ الْإِمَامِ إِلَّا أَنْ يَكُونَ الْإِمَامُ مِمَّنْ يُتَّقَى فَلَا تَقْطَعْ صَلَاتَكَ وَ لَا تَجْعَلْهَا نَافِلَةً وَ لَكِنِ اخْطُ إِلَى الصَّفِّ وَ صَلِّ مَعَهُ فَإِذَا قَامَ الْإِمَامُ إِلَى رَابِعَتِهِ فَقُمْ مَعَهُ وَ تَشَهَّدْ مِنْ قِيَامٍ وَ سَلِّمْ مِنْ قِيَامٍ
My father – May Allah be pleased with him – wrote to me in a letter: Do not pray behind anyone except two people: the first of them being someone whose religious status and piety you trust, and the other being someone whose sword, assault and repulsiveness against religion you fear. Pray behind him (the latter) out of dissimulation, and tolerance, but say the call to prayers for yourself, and stand, and recite for yourself, while not following them in it. So when you are near the end of the recitation of a sūrah before him, then leave one verse, and praise Allah (‘azwj). Once the Imām goes in rukū’, then read the last verse and do the rukū’ with him. If you fear that you will not be able to recite a complete sūrah before the Imām goes into rukū’, then say the adhān and iqāmah with that which the Imām had omitted and then go into rukū’.
If you are in a supererogatory prayer, and a congregational prayer gets established, then cut your prayers short and join the obligatory prayer, and if you are in an obligatory prayer then do not cut it (if there is a congregation established), but change it into a supererogatory prayer, and say the taslīm after the two units, and then join the congregation prayers with the Imām. If the Imām is not one who one must dissimulate from, then in that case do not cut your prayers, or change it into a supererogatory prayer, but rather move towards the row of prayers and pray alongside him. If the (non-Shī’a) Imām stands up while one is in their fourth unit, then stand up with him and recite the tashahhud, and taslīm while standing up. 
The description given by Ibn Bābuwayh is invaluable, as it makes it clear that one is essentially praying an individual prayer, and is only making it appear as if they are praying in congregation with them. Shaykh al-Ṣadūq in his al-Hidayah fi al-Uṣūl wa al-Furū’ reiterates a similar opinion as his father, but in a summarized manner. Soon after him, we find Shaykh al-Mufīd (d. 413 AH) addressing this matter in passing while discussing the subject of Friday prayers. In his jurisprudential work al-Muqni’ah he writes:
و يجب حضور الجمعة مع من وصفناه من الأئمة فرضا و يستحب مع من خالفهم تقية و ندبا
It is obligatory to participate in the Friday prayers behind an Imām who meets the qualities of what we have described, and it is desirable to pray behind an Imām who opposes them (i.e. he is from the Ahl al-Sunnah), due to dissimulation and recommendation.
While listing out the criteria for who one can pray behind, Shaykh al-Ṭūṣī (d. 460 AH) – a student of al-Mufīd – mentions that one can only pray behind a non-Shī’ī when in a state of dissimulation. In his al-Nihāyah, he writes:
و لا تصلّ إلّا خلف من تثق بدينه. فإن كان غير موثوق بدينه، أو كان مخالفا لك في مذهبك، صلّيت لنفسك، و لم تقتد به. و لا تصلّ خلف النّاصب، و لا خلف من يتولّى أمير المؤمنين، إذا لم يتبرأ من عدوّه، إلّا في حال التقيّة
And do not pray behind one unless you have attained trust in the soundness of their religion. If a person is not reliable in their religion, or they are an opponent of your religion, then pray on your own, and do not follow him (in congregation).
And do not pray behind a nāṣib, and one who loves Amīr al-Mu’minīn, but does not disassociate from his enemies, except in a state of dissimulation.
Another work of Shaykh al-Ṭūṣi is his al-Mabsūṭ. This is a comprehensive work comprised of all chapters of jurisprudence and is an important book for understanding his views. In it, he writes:
و إذا صلى خلف من لا يقتدى به قرأ على كل حال سمع القراءة أو لم يسمع. فإن كان في حال تقية أجزأه من القراءة مثل حديث النفس، و لا يجوز أن يترك القراءة على حال، و إن لم يقرأ أكثر من الحمد وحدها كان جائزا، و لا يجوز أقل منها، و إذا فرغ المأموم من القراءة قبل الإمام سبح مع نفسه. و يستحب أن يبقى آية من السورة فإذا فرغ الإمام قرأ تلك الآية و ركع عن قراءة
When someone prays behind one who is not meant to be followed (in congregation), he is to recite (the sūrahs) in any condition, whether he can hear the recitation (of the Imām) or not. If this is done in a state of dissimulation, then even mere murmuring of the recitation to one’s self is sufficient. Recitation (of the chapters) cannot be abandoned in any situation. If one does not recite more than just the al-Ḥamd, it is allowed, but less than it is not allowed. If the follower finishes their recitation before the Imām, they are to glorify Allah to themselves. It is recommended to leave one verse of a chapter, and when the Imām is done with his recitation, the follower can recite the last verse and go into rukū’ after their recitation.
Also, in the 5th century was the scholar Ibn al-Barrāj (d. 481 AH). He speaks of this discussion in his al-Muhadhdhab as follows:
و من صلى خلف من لا يقتدى به و كان عليه تقية و لم يتمكن من قراءة أكثر منها كان جائزا و يجزيه أيضا ان كان عليه تقية ان يكون قراءته مثل حديث النفس و لا يجوز له ترك القراءة على حال، و إذا سبق الإمام الذي لا يقتدى به الى الفراغ من السورة فالأفضل ان يبقى منها آية فإذا وصل الامام إليها تممها هو بذلك معه، فاذا فرغ منها قبله فينبغي له ان يسبح الله تعالى و يحمده الى حين فراغه من القراءة
And one who prays behind an Imām who is not meant to be followed, and dissimulation is required by the follower and it is not possible for him to recite more than it (i.e. the first sūrah), it suffices. Murmuring the recitation to one’s self also suffices if it is due to dissimulation, but in any case, abandoning the recitation is not allowed. If he finishes reciting the chapters before the Imām who is not meant to be followed, then it is better to leave the last verse from it, and when the Imām reaches the end of his recitation, the follower can complete the last verse with the Imām. However, if the follower finishes reciting the chapter before the Imām, then it is required for him to glorify Allah (swt) and to praise him, until the Imām ends his recitation.
Post-Classical Scholars (500 – 966 AH)
According to one popular division of scholars, the era between 6th to 10th century hijri is not considered a time period of the classical scholars. On the forefront of these was Ibn Idrīs al-Ḥillī (d. 598). In his most important work, al-Sarā’ir he writes:
فأمّا من يؤتم به على سبيل التقية، ممّن ليس بأهل للإمامة، فلا خلاف في وجوب القراءة خلفه، إلا أنّه لا بدّ له من إسماعه أذنيه، و ما ورد أنّه مثل حديث النفس فإنه على طريق المبالغة و الاستيعاب، لأنّه لا يسمّى قارئا
As for the one who follows him (i.e. a non-Shī’ī Imām) out of dissimulation – one who does not deserve to lead the prayers – then there is no difference of opinion in that it is obligatory to recite (the sūrahs) behind him, rather it is necessary for him (i.e. the Shī’ī follower) to hear the recitation with his own two ears. As for what has been mentioned in terms of just murmuring to one’s self, then that is out of exaggeration and assimilation, because in actuality such a person is not referred to as a ‘reciter’.
Muḥaqqiq al-Ḥillī (d. 676 AH / 1277 CE) one of the greatest 7th century hijrī Shi’ī scholar, writes in his al-Mukhtaṣar al-Nāfi’:
الثالثة: من صلى خلف من لا يقتدى به أذن لنفسه و أقام. و لو خشي فوات الصلاة اقتصر من فصوله على تكبيرتين و قد قامت الصلاة
Thirdly: One who prays behind a person who is not meant to be followed, they are to recite the adhān for themselves, and as well as the iqāmah. If, however, they fear that the prayers will be missed, they are to suffice with just saying the two takbīrs and qad qāmat al-ṣalāt. 
In this ruling, we observe that praying behind an Ahl al-Sunnah Imām in certain situations is already being taken for granted. Thus, Muḥaqqiq al-Ḥillī discusses one of the branches of this matter, which is whether you can rely on the adhān and iqāmah of someone from them or is there still any merit in reciting it for yourself as is the case when reciting a prayer that is not congregational. A contemporary to Muḥaqqiq al-Ḥillī, Yaḥya bin Sa’īd Al-Ḥillī (d. 690 AH), who was a nephew of al-Muḥaqqiq, and whose maternal grandfather was Ibn Idrīs al-Ḥillī, writes in his al-Jāmi’:
و من صلى خلف من لا يقتدى به، اذن لنفسه و اقام […] و إذا دخل المسجد و فيه من لا يقتدى به، و خاف فوت الصلاة بالاشتغال بالأذان و الإقامة اقتصر على التكبيرتين، و قد قامت الصلاة، و روى انه يقول حي على خير العمل دفعتين لأنه تركه
As for one who prays behind one who is not meant to be followed, then they are to recite the adhān and iqāmah for themselves. […] and if one enters the mosque and in there is a person leading who is not meant to be followed, and a person fears missing the prayers if they become occupied with reciting the adhān and iqāmah, then they should suffice with two takbīrs, and saying qad qāmat al-ṣalāt. It has also been reported in a tradition that the person should say ḥayya ‘ala khayr al-‘amal twice because the Imām leading the prayers had abandoned it.
‘Allāmah al-Ḥillī (d. 726 AH/1326 CE) who was perhaps the greatest Shī’ā scholar of his time, writes in his Taḥrīr al-Aḥkām al-Sharī’ah:
إذا دخل المسجد، و كان الإمام ممّن لا يقتدى به أذّن لنفسه و أقام،و لم يعتدّ بأذانه، و لو صلّى خلفه، فإن خشي فوات الصلاة معه، اقتصر على التكبيرتين و على قوله: «قد قامت الصلاة». و روي أنّه يقول: «حيّ على خير العمل» مرتين
If one enters the mosque and the Imām is someone who is not meant to be followed, one is to recite the adhān themselves and as well as the iqāmah, and the adhān of the Imām does not count for anything. If, however, a person prays behind him and fears missing the prayers, then they should suffice with two takbīrs, and saying qad qāmat al-ṣalāt. It has also been reported in a tradition that the person should say ḥayya ‘ala khayr al-‘amal twice.
In a discussion concerning whether one is meant to recite the chapters behind an Imām who is not meant to be followed, ‘Allāmah al-Ḥillī writes in another work Talkhīṣ al-Marām fi Ma’rifah al-Aḥkām:
و تجب خلف من لا يقتدى به
And recitation is obligatory behind someone who is not meant to be followed.
This is in line with verdicts of all previous scholars mentioned so far. All of them deem recitation to be obligatory in all scenarios. In his Mukhtalaf al-Shī’a, after describing what Shaykh al-Ṭūṣī’s opinion is regarding a person who is already performing their obligatory prayers individually, and an Imām who is not meant to be followed begins his congregational prayers, al-Ḥillī cites Ibn Bābuwayh’s view and comments on it as follows:
و قال علي بن بابويه- رحمه اللّه-: فاذا صلّيت أربع ركعات و قام الإمام إلى رابعته فقم معه و تشهد من قيام و سلّم من قيام
و الأقرب عندي التفصيل، فان تمكن المأموم من تخفيف الشهادتين جالسا وجب، و إلا جاز له القيام قبله للتقية، و فعل ما قاله علي بن بابويه. أمّا الأوّل: فلأنّه لولاه لكان قد زاد في الصلاة متعمدا فتبطل صلاته. و أمّا الثاني: فلأنّه غير متمكّن من التشهّد جالسا فجاز قائما كالخائف
‘Alī bin Bābuwayh (ra) says: If you have prayed four units, and the Imām stands up for his fourth unit, then stand up with him and recite the tashhud while standing, and the taslīm while standing.
What is more correct according to me (i.e. ‘al-Ḥillī) is differentiating between two scenarios. If it is possible for the follower to shorten the two testimonies while sitting, then it is obligatory on him to do so, otherwise it is permissible to stand up due to dissimulation. Then he does what ‘Alī bin Bābuwayh has said. As for the evidence for the first case: It is because if he does not do that, then he would have added something to the prayers on purpose, and his prayers would have been invalidated. As for the second case: Then that is because it is not possible for him to recite the testimony while sitting, and thus it is allowed while standing, like someone who is fearful (i.e. someone who is reciting the prayers of fear).
Al-Shahīd al-Awwal (d. 768/1385 CE) in a number of his works speaks of this ruling. In his al-Bayān and al-Dhikra, he writes:
يستحب حضور جماعة أهل الخلاف استحبابا مؤكداً
It is recommended to participate in the congregation of the opponents, and this recommendation is emphasized.
It is interesting to note that a scholar like al-Shahīd al-Awwal had significantly more interaction with the Sunnīs compared to some of the previous scholars cited. Under such circumstance, he is even more explicit in al-Durūs, where he writes:
و يستحبّ حضور جماعة العامّة كالخاصّة بل أفضل، فقد روي من صلّى معهم في الصفّ الأوّل كان كمن صلّى خلف رسول اللّه صلّى اللّه عليه و آله، فيه و يتأكّد مع المجاورة، و يقرأ في الجهريّة سرّا و لو مثل حديث النفس، و يسقط لو فجأه ركوعهم، فيتمّ فيه إن أمكن و إلّا سقط
It is recommended to participate in the congregational prayers of the ‘Āmmah (i.e. Ahl al-Sunnah), just like it is with the Khāṣṣah (i.e. the Shī’a) – in fact it is more meritorious. It has been reported that he who prays with them in the first row, is like the one who prayed behind the Messenger of Allah (p). This recommendation is emphasized when one has access to such a prayer in their vicinity. In a prayer where the chapters are meant to be recited loudly, he is to recite in a low voice, even if it means to murmur the recitation to one’s self. The (obligation of this) recitation will drop if their rukū’ occurs suddenly. He is to complete it in the rukū’ if possible, otherwise it drops.
In the 10th century hijrī, we find a group of believers inquiring al-Shahīd al-Thānī (d. 966 / 1559 CE) regarding their prayers behind a non-Shī’ī. Their confusion lays in whether praying in congregation implies making an intention of congregation, or is one meant to be reciting their own individual prayer while simply following the Imām in his actions. To this, he responds as follows:
و أمّا الصلاة خلفَ المخالف ففيها ثواب عظيم، بل هي أفضلُ و أكثرُ ثواباً مِن جَماعة المؤمنين؛ لأجل التقيّة، و حقيقتها أن يقفَ المصلّي معهم منفرداً قارئاً لنفسه و لو في نفسه إذا خافَ الإظهار، و يتابِعَهم في الركوع و السجود حتّى لو سبقوه بالقراءة و ركعوا سقط عنه باقي القراءة، و أدركَ بالصلاة معهم في الصفّ الأوّل ثوابَ مَن صلّى مع النبيّ صلّى الله عليه و آله في الصفّ الأوّل، كما ورد في الأخبار. و لهذه الصلاة أحكام خاصّة ضاق الوقتُ عنها
As for the prayers behind an opponent, then there is great reward in it, rather it is greater and has more reward than praying in the congregation of the believers, due to dissimulation. Its reality is that a prayer stands alongside them in his individual prayers, reciting for himself, albeit only a low recitation for himself if he fears himself becoming apparent (to others), and he follows him in the rukū’ and sujūd, even if they finish the recitation before him and go into rukū’, in which case the obligation of the remainder of the recitation drops. One who joins their prayers in the first row, the reward for him is the reward for one who prayed with the Prophet (p) in the first row – as it has been reported in a narration.
While al-Shahīd al-Thānī lived during a time when the Safavid dynasty began ruling over Iran, he himself is not considered a Safavid scholar, as he did not live under their reign. Thus, he has not been included in the list of scholars that follows. Furthermore, the case of al-Shahīd al-Thānī is similar to al-Awwal’s, from the perspective of having significantly more interaction with Sunnīs than some of the previous scholars cited.
Ṣafavid Era Scholars (900 AH – 1135 AH / 1501 – 1736 CE)
From amongst the Ṣafavid era scholars, ‘Allāmah Muḥammad Taqī al-Majlisī (d. 1070 AH/1660 CE) – the father of the renowned ‘Allāmah Muḥammad Bāqir al-Majlisī – holds an esteemed position. He has two important works: one an Arabic commentary on Shaykh al-Ṣadūq’s work al-Faqīh, and another a Persian translation and commentary on the same book. In the former, we find him writing in under a narration he considered to be authentic:
يفهم منه استحباب تقديم الصلاة و إعادتها معهم متوضئا تقية كما يدل عليه ما رواه الكليني في الصحيح، عن محمد بن إسماعيل
It is understood from this narration that there is istiḥbāb (recommendation) in praying first, and then repeating it with them in the state of wuḍū while in a state of dissimulation. This meaning is also understood in a report al-Kulaynī records in an authentic tradition from Muḥammad bin Ismā’īl. 
In his Persian commentary and translation of the same work, he gives a thorough explanation on the treatise written by Ibn Bābūwayh to his son Shaykh al-Ṣadūq and alludes to the same point he makes in his Arabic commentary. Shaykh Ṣāleḥ Mazandarānī (d. 1081 AH), famous for his invaluable commentary on al-Kulaynī’s work al-Kāfi and a contemporary to al-Majlisī I, makes it clear that:
اتّفق الأصحاب على استحباب حضور جماعة أهل الخلاف تقيّة و صورة الائتمام بهم استحباباً مؤكّداً، بل قد يجب
The jurists have a consensus upon the recommendation of being present in the congregation prayers of those who are against us, out of dissimulation and in the form of following him, and this recommendation is emphasized, and in fact sometimes it is obligatory. 
The well-known Ṣafavid era philosopher, exegete and an Akhbārī jurist Mulla Muḥsin Fayḍ Kashāni (d. 1091 AH / 1681 CE) also touches upon this issue. In his work on jurisprudence, he reiterates what previous scholars had said:
يستحبّ حضور جماعة أهل الخلاف استحباباً مؤكّداً
It is recommended to be present in the congregation of those who are against us, and this recommendation is emphasized. 
Post-Safavid Scholars (12th – 15th Century AH / 18th – 21st Century CE)
Perhaps the last prominent Akhbārī scholar was Shaykh Yūsuf al-Baḥrānī (d. 1186 AH / 1772 CE), who spent the last years of his life in the city of Karbalā. In his magnum opus, al-Ḥadāiq al-Nāḍirah, he writes:
قد استفاضت الأخبار بأنه يستحب حضور جماعة المخالفين استحبابا مؤكدا
The reports have reached a state of abundance, stating it is recommended to be present in the congregation of the opponents, and the recommendation is emphasized.
Following al-Baḥrānī, was the prominent Uṣūlī scholar Shaykh Kāshif al-Ghiṭā’ (d. 1227 AH / 1812 CE). He was a direct student of Shaykh al-Waḥīd al-Bihbahānī (d. 1205 AH / 1791 CE), a personality known for dismantling the Akhbārī school of thought. As such Shaykh Kāshif would be considered a first-tier Uṣūlī scholar after a few centuries of dominance by the Akhbārīs. He writes in an important work of his:
و لا بدّ من نيّة الانفراد معهم، و إظهار الدخول في جماعتهم، ثمّ يأتي بما أمكنه، مع اللّحوق بأئمّتهم من قراءة و لو كحديث النفس أو أذكار، أو غيرها.و الأفضل أن يصلّي الفريضة قبل، ثمّ يحضر معهم، ثمّ له أن يعكس، و يجعل الصلاة معهم سُبحة
It is required to do an intention of an individual prayer when praying with them, and making it appear as if one is in congregation with them. Then a person should perform whatever he is able to – while following their Imāms – such as the recitation, even if it is a mere murmur to one’s self, short phrases of prayer (dhikrs), or something other than it. It is more meritorious for a person to perform the obligatory prayers first (elsewhere), and then join them in their congregation, then he is allowed to do the opposite, by making his prayers with them in congregation as a form of glorification (i.e. he can appear to be praying in congregation, but in fact is doing tasbīḥ).
Somewhat contemporary to al-Ghiṭā’, but in the city of Qom, was Shaykh Mīrzā al-Qumi (d. 1231 AH / 1816 CE), also known as Ṣāḥib al-Qawānīn. In one of his works, he writes:
يستحبّ حضور جماعة أهل الخلاف استحباباً مؤكّداً للأخبار الكثيرة
It is recommended to be present in the congregation of the opponents, and this recommendation is emphasized, due to an abundant amount of reports regarding it.
In a 4-volume work titled Raṣāil Āl Ṭūq al-Qaṭīfī, a number of treatises written by Shaykh Aḥmad bin Ṣāliḥ al-Qaṭīfī (alive in 1245 AH) have been collected and compiled. Though extensive details are not known about his life, we do know who some of his teachers and as well as his students were. In any case, in one of his works he explains this ruling as follows:
و اعلم أنه قد يجب حضور جماعة أهل الخلاف كفاية أو عيناً و إن لم تصحّ نيّة الاقتداء بهم، و لا يجوز أن يصلّي معهم بغير وضوء، فإن لم يتمكّن يتيمّم، فإن تعذّر فلا ينوي الصلاة، و أرِهم كأنّك تركع و تسجد و لا تركع و لا تسجد. و لو اضطررت للدخول معهم بغير نيّة الصلاة فلا تستخفّ بها في حال. و من نوى الائتمام بهم لم تصحّ صلاته فإنهم كالخشب المسنّدة
و يلزم المصلّي معهم القراءة و لو سرّاً، و يكفي معهم مثل حديث النفس. و يسقط الجهر في الجهريّة، و ينصت إلىٰ قراءة إمامهم إذا سمعها، فإذا سكت قرأ، و إن لم يسكت قرأ في نفسه. و من فرغ من السورة قبل إمامهم تخيّر بين أن يكمل السورة أو يذكر اللّٰه تعالىٰ حتّى يركع، و بين أن يؤخّر آية من آخر السورة و يذكر اللّٰه حتّى يركع إمامهم فيقرأها و يركع. و من لم يتمكّن من قراءة السورة سقطت عنه إجماعاً
Know that sometimes it becomes obligatory to participate in the congregation of the opponents – either an obligation that suffices through a few people, or an obligation that is upon everyone – even though an intention of praying in congregation behind them is not correct. It is not allowed to pray besides them without wuḍū, and if that is not possible then perform the tayammum, and if that is not possible, then do not do an intention of the prayer and pretend to show them that you are going into rukū’ and prostration while you are not truly doing a rukū’ or prostration. If you are required to enter in congregation with them without the intention of prayers, do not take it lightly in any case. As for the one who makes an intention to follow them in congregation, his prayers is not valid, because they are like dry logs set reclining [against a wall]. 
It is required of the person praying with them, to recite the chapters albeit quietly, and simply murmuring to one’s self also suffices. The requirement of reciting loudly drops in a prayer where it is required to recite loudly, and one is to listen to the recitation of the Imām if one can hear it. If the Imām is silent, one should recite, and if the Imām is not silent, one should recite for themselves.
As for the one who finishes the recitation of a chapter before the Imām does, he is to choose between completing the chapter and then remembering Allah, until the Imām goes into rukū’, or to leave out the last verse of the chapter and remember Allah, until the Imām goes to rukū’, in which case he should recite the last verse and go into rukū’. If one is not able to recite a complete chapter, its obligation drops for him – based on consensus. 
Shaykh Muḥammad Ḥasan Sharīf al-Iṣfahānī al-Najafī (d. 1266 AH / 1850 CE) also known as Ṣāḥib al-Jawāhir, expresses the same opinion in an extensive discussion on the topic. A relevant portion of it is as follows:
و أما لو كان الامام ممن لا يقتدى به لأنه مخالف وجبت القراءة في الصلاة خلفه تقية كما صرح به جماعة من الأصحاب بل لا أجد فيه خلافا بينهم كما اعترف به في المنتهى و عن السرائر، بل نسبه في الحدائق إلى عمل الأصحاب تارة، و بزيادة «كافة» أخرى، لانتفاء القدوة المعتبرة في ضمان الإمام القراءة، بل هو منفرد حقيقة
If the Imām is one who is not meant to be followed, because he is an opponent, then recitation of the chapters in the prayers behind due to dissimulation, is obligatory. This is in accordance to what a large number of jurists have said, in fact, I have not found a difference of opinion on this matter amongst them, just like the same has been admitted in al-Muntaha and al-Sarā’ir. As a matter of fact, in al-Ḥadā’iq this act has been attributed to the companions at times, and at other times the attribution to them is mentioned with an additional term “all of them”. This (verdict is the way it is) due to the absence of a reliable guarantee given to the Imām reciting the chapters, and as such, the person is praying individually in reality.
Shaykh al-Anṣārī (d. 1281 AH / 1864 CE) who took over general leadership of the Shī’a after Ṣāḥib al-Jawāhir, and is known for moving Shī’ī legal theory and jurisprudence to new fronts, writes the following:
فإنّه يجب القراءة خلفه؛ لاختصاص أدلّة السقوط بما إذا كان خلف المرضي، مضافا إلى عموم أنّ الأئمة المخالفين بمنزلة الجدر، نعم يعذر المأموم في ترك الجهر في الجهرية اتّفاقا فتوى و نصّا، و في بعض الروايات: يكفيك مثل حديث النفس
…it is obligatory to recite behind him (an Ahl al-Sunnah Imām), because the evidence that discusses the dropping of the recitation (in congregation) are specific to when a person is praying behind someone who is approved of. Additionally, there are general principles that imply that the Imāms of the opponents are like a wall. Yes, at times a follower will have an excuse to not recite loudly in a prayer where one is meant to recite loudly, and there is a consensus of verdict on this and as well as the explicit reports. In some of the narrations it has been mentioned: Murmuring to the self is sufficient for you. 
تجب القراءة خلف الإمام الغير المرضي، لعدم القدوة إلّا صورة
It is obligatory to recite behind an Imām who is not approved of, because actual imitation (of the Imām) is absent, and exists only in an apparent form. 
Moving on to the 20th century of the common-era, we see ‘Abd al-Ḥusayn Sharaf al-Dīn al-Mūsawī (d. 1377 AH/1957 CE) being the first to express sentiments that perhaps it is allowed to perform these prayers with the intention of congregation. Al-Mūsawī was known for being a strong advocate of Shī’ī and Sunnī unity during this time. In one of his works he writes:
ويثاب المصلي منا خلف الامام السني كما يثاب بالصلاة خلف الشيعي، والخبير بمذهبنا يعلم انا نشترط العدالة في امام الجماعة اذا كان شيعياً، فلا يجوز الائتمام بالفاسق من الشيعة ولا بمجهول الحال، اما السني فقد يجوز الائتمام به مطلقا.
And a person performing a prayer from amongst us behind a Sunnī Imām gets rewarded just like he is rewarded for praying behind a Shī’ī. Anyone well-versed in our school of thought will know that we consider ‘adālah – a condition in the Imām of congregation if he is a Shī’a – and one is not allowed to follow a Shī’a transgressor and neither someone whose condition is not known. As for a Sunnī, following them is allowed in all cases (i.e. ‘adālah is not a condition). 
Another 20th century scholar who is credited for producing hundreds of students around the world is Sayyid al-Khū’ī (d. 1413 AH / 1992 CE). In a series of questions he was posed regarding this matter, his responses were as follows:
سؤال 256: هل يجوز الائتمام بالمخالف و بنية الجماعة، مع العلم بأن الإمام للجماعة حليق اللحية؟
الخوئي: لا تعتبر العدالة في مفروض السؤال
Q 256: Is following an opponent with the intention of congregation allowed, while knowing that the Imām of congregation has a shaved beard?
A: ‘Adālah is not a condition in the question posed.
سؤال 257: هل الصلاة خلف الإمام المخالف مستحبة و ما كيفيتها، و هل تجزئ عن الفريضة أم لا؟ و إذا كانت الصلاة بالمتابعة ما ذا يفعل المأموم حينما ينهى القراءة و الإمام لم ينته من ذلك، و كذا لو كانت الصلاة جهرية هل يجوز له أن يخفت أم لا؟ و هل يقيد ذلك كله في حالة التقيّة أم لا؟
الخوئي: نعم يستحب و يقرأ القراءة الواجبة لنفسه بالإخفات، و لا بأس بالفراغ قبل فراغ الإمام عنها و يصبر و يركع معه، و الإخفات مطلقا لقراءته، و لا يتقيّد بأمر ما سوى كونه مسلما من غير الإمامية، فإذا كان الإمام مخالفا لا يتقيد كل ما ذكر بحال التقية
Q 257: Is a prayer behind an opponent Imām recommended, and how is it performed, and does it suffice for an obligatory prayer or not? If the prayer is by remaining in sync, what should a follower do when they complete the recitation, while the Imām has not finished it yet? Likewise, if the prayer is one where one is meant to recite loudly, is it allowed for the follower to recite quietly? Are all these rulings restricted to cases of dissimulation or not?
A: Yes, it is recommended, and a person must recite the chapters for himself quietly. There is no issue in finishing the recitation before the Imām finishes them, and one can wait patiently and then go into rukū’ with him. His recitation is to be done quietly in all cases. The prayers are not conditioned to anything except that the person leading the prayers is a non-Imāmi Muslim. So, if the Imām is an opponent, not everything that has been mentioned is conditioned by dissimulation.
س 217: إذا صلّى جماعة مع العامة فهل تترتب أحكام الجماعة كما في جماعة المؤمنين (كالرجوع الى الامام الحافظ عند الشك في الركعات، و كاغتفار زيادة الركوع إذا قام قبل الامام سهوا فيرجع للمتابعة مثلا)؟
الخوئي: نعم تترتب الأحكام، سوى القراءة فإنه لا يتحمّلها الامام، و لا بدّ من القراءة، و اللَّه العالم
Q 217: If one prays in congregation with the ‘Āmmah, do the rules of congregation apply, like in the congregation of believers (such as referring to the Imām in a case of doubt between the units of prayers, and like the pardon given to one who adds an extra rukū’ if he stands up before the Imām forgetfully, and then returns back in order to be in sync, for example)?
A: Yes, the rules of congregation apply, except recitation (of the chapters), because the Imām does not bear responsibility for it, and thus there is no choice, but to recite – and Allah knows best.
س 213: هل هناك شروط لصلاة الجماعة مع أبناء العامة في مساجدهم؟
الخوئي: يجوز الاشتراك في جماعة هؤلاء في مساجدهم و غيرها، و تصح الصلاة معهم بشرط الإتيان بالقراءة في نفسه، و لا يعتبر فيه شروط خاصة، و اللَّه العالم
Q 213: Are there any conditions for congregation prayers with the ‘Āmmah in their mosques?
A: Participating in their congregation is allowed, in their mosques or elsewhere, and prayers with them is correct, with the condition that a person does the recitation himself. There are no other specific conditions – and Allah knows best.
س 214: ما هي فلسفة صلاة الجماعة مع الإخوان السنّة؟
الخوئي: منها إظهار الوحدة في صفوف المسلمين، و اللَّه العالم
Q 214: What is the wisdom behind praying in congregation with the Sunnī brothers?
A: From the wisdoms, is the display of unity amongst the ranks of the Muslims – and Allah knows best.
Contemporary to Sayyid al-Khū’ī was the astounding scholar Imām al-Khomeinī (d. 1409 AH / 1989 CE). Known for his innovative discussions regarding the principle of dissimulation, his rulings on this matter are also unique:
در مواردی که دستور فرموده اید «در نماز جماعت برادران اهل سنت شرکت کنیم«؛ آیا این نماز از نظر نیت و غیره مثل نماز جماعت شیعه است؟
بسمه تعالی، به هرنحو آنها عمل می کنند انجام دهند
Q: Given that you have said “we must participate in the congregational prayers of the Ahl al-Sunnah brothers”; is this prayers with respect to its intention and other rules, like the congregational prayers of the Shī’a?
A: In the name of Allah – however they (the Ahl al-Sunnah) carry their prayers out, the followers should carry it out like that.
سؤال 3309 2. در نماز با مخالفین باید نیت اقتدا کرد؟
بسمه تعالی، مثل سایر جماعات است و باید اقتدا کرد.
Q: When praying alongside the opponents, does one need to do an intention of following?
A: In the name of Allah – the prayers is like all other congregational prayers, and one must do an intention of following.
Perhaps no jurisconsult enjoys greater following today than Sayyid al-Sistānī. Like his teacher Sayyid al-Khū’ī, his rulings permit the praying in congregation behind a Sunnī, though with a slight difference of opinion from his teacher:
السؤال1: هل تصح صلاة الإمامي إذا اقتدى فيها ببعض أهل السنة في الصورتين التاليتين
أ – أن يكون ذلك بإقتضاء التقية؟
ب – أن يكون ذلك بإقتضاء بعض المصالح العامة كالتآلف معهم لأجل الحفاظ على الوحدة الإسلامية.
الجواب: تجوز الصلاة خلفهم ولكن لابد للمأموم أن يقرأ لنفسه إخفاتاً إن أمكنه وإلا يقرأ في نفسه ويجوز له التكتف إذا اقتضته التقية كما يجوز له السجود على ما لا يصح السجود عليه عندنا إذا لم يتيسر في مكانه ما يصح السجود عليه كالبارية فإن تيسر وجب اختياره
Q 1: Is a prayer of an Imāmī valid if he follows an Ahl al-Sunnah in the following two scenarios:
a) It is due to dissimulation
b) It is due to other general benefits, such as developing harmony with them in order to safeguard Islamic unity
A: Prayers behind them is allowed, however, the follower must recite the chapters for themselves in a low voice if possible, otherwise he can murmur them to himself. Folding of the hands if also only allowed if dissimulation necessitates it, like just it is allowed to prostrate on something on which prostration is not generally allowed according to us if it is not possible to replace it with something on which it is permissible to prostrate on, like a straw mat. If it is possible, then it is obligatory to choose it as a place of prostration.
السؤال2: هل في الصلاة خلف غير الامامي لرعاية التآلف بين المسلمين يقصد الامامي الائتمام وتترتب أحكام الجماعة؟
الجواب: لا ضير في نية الاقتداء بالامام منهم ولكن من دون ترتيب أحكام الجماعة
Q 2: In a prayer behind a non-Imāmi for the purpose of developing harmony between the Muslims, can an Imāmī make an intention to follow and are the rules of congregation prayers applied?
A: There is no harm in an intention of following an Imām from them, but the rules of congregation are not applied.
In order to understand what it means for the rules of congregation not applying, one of the aforementioned questions to Sayyid Khū’ī may be of benefit. This appears to be a reference to rules of congregation that are generally enacted once a congregational prayer has begun. For example, when praying behind a Shī’ī Imām, if one were to accidentally stand up from rukū’ before the Imām, and then they returned back to rukū’, this would not harm a person’s prayer. This is one example of a law pertaining congregation, whereas in an individual prayer, returning back to rukū’ would invalidate the prayers.
While Sayyid Khū’ī believed that all congregational rules – except recitation – apply in a prayer behind a Sunnī, Sayyid al-Sīstānī is of the opinion that none of the laws of congregation, which are generally enacted behind a Shī’ī Imām, apply in a prayer behind a Sunnī. This however, does not imply anything about not having an intention of congregation, and the prayers being an individual. Of course, the response of Sayyid al-Sīstānī is itself apparent in suggesting that an intention of congregation does not harm the prayers and that it suffices.
One may wonder, what difference would an intention of congregation make if, according to Sayyid al-Sīstāni, no rules of congregation are applied, and the recitation is also meant to be conducted by the follower. In other words, whether one prays individually while their apparent form of prayers seems to be such that they are following a Sunnī Imām, or whether they do an intention of congregation behind them, yet are still in, in fact, citing the chapters and saying the adhkār themselves – it makes no real difference.
This question presumes that there is no inherent benefit to having an intention of congregation to begin with. This ignores the fact that intentions themselves play a direct role in attaining reward or receiving punishments, or at other times they can validate one’s actions and their absence can nullify them. In any case, a detailed response to this would require a discussion on the essence of what differentiates a congregational prayer from an individual prayer, and what role intentions play in our acts of worships. This discussion is outside the scope of such a paper.
From amongst the pool of contemporary jurisconsults that enjoys vast following, is Sayyid ‘Alī al-Khāmenaī. His rulings on this matter can be seen as distinct from some of the other contemporary scholars, as he even permits praying in accordance to their times, and on carpets, if it necessitates Islamic unity. Some of his responses are as follows:
س 599: آیا نماز جماعت پشت سر اهل سنت جایز است؟
ج: نماز جماعت براى حفظ وحدت اسلامى، جايز و صحيح است
Q 599: Is congregational prayer being the Ahl al-Sunnah allowed?
A: Congregational prayer for the sake of Islamic unity, is allowed and correct.
س 601: در مکانهای مشارکت و رفت و آمد با برادران اهل سنت، هنگام شرکت در نمازهای روزانه، در بعضی از موارد مانند آنان عمل میکنیم، مثل نماز بهصورت
تکتّف و عدم رعایت وقت و سجده بر فرش، آیا این نمازها احتیاج به اعاده دارند؟
ج: اگر حفظ وحدت مقتضى انجام آن کارها باشد، نماز صحيح و مجزى است، حتى اگر سجده بر فرش و مانند آن باشد، ولى تکتّف در نماز جايز نيست، مگر اينکه ضرورت آن را اقتضا کند
Q 601: In places where there is interaction with the Ahl al-Sunnah brothers, while participating in the daily prayers, in some cases we act like them. For example, we fold our hands, and do not pray in accordance to our time, and prostrate on the carpet – do these prayers require repetition?
A: If the safeguarding of Islamic unity was the cause of these acts, then the prayers was correct and allowed, even if it meant prostrating on carpet and its like. However, folding of the hands is not permissible, unless something necessitates it.
س 603: مشارکت ما شیعیان در نماز جماعت مساجد کشورهای دیگر با برادران اهل سنت که دست بسته نماز میخوانند، چگونه است؟ آیا تبعیت از آنان در تکتف بر ما واجب است یا آن که باید نماز را بدون تکتف بخوانیم؟
ج: اقتدا به اهل سنت، براى رعايت وحدت جايز است و نماز خواندن با آنها صحيح و مجزى است، ولى تکتف واجب نيست و بلکه جايز نيست، مگر در صورتى که ضرورتى آن را اقتضا کند
Q 603: How is the participation of us Shī’as meant to be in the congregational prayers in the mosques of different countries with the Ahl al-Sunnah brothers, who perform their prayers with folded hands? Does following them make it obligatory upon us to also fold our hands, or are we supposed to pray without folding our hands?
A: Following an Ahl al-Sunnah, for the purpose of safeguarding Islamic unity is permissible, and the prayers performed alongside them is correct and allowed. However, folding of the hands is not obligatory, and in fact it is not allowed, unless something necessitates it.
Under a question posed to Ayatullah Makārim al-Shīrāzī regarding praying behind a Sunnī in a country other than Saudi Arabia, the response was as follows:
پرسش : حکم اقتدا به امام جماعت اهل سنت در غیر کشور عربستان مثل کشورهای عربی و همچنین نماز خواندن در مساجد آنان با جماعت یا فرادی و سجده بر فرش چیست؟
پاسخ : در مواقعی که با آنها هستید می توانید به جماعت اقتدا کنید و نماز صحیح است
Question: What is the ruling on following a Sunnī Imām in congregation, in a country other than Saudi Arabia, for example other Arab countries; and likewise, what is the ruling on praying in their mosques, whether individually or in congregation, and prostrating on carpet?
Answer: In times when you are with them, you are allowed to follow them in congregation, and the prayers is valid.
From amongst the leading jurisconsults of Isfahān with regular classes is Ayatullah Ḥusayn Maẓāhirī. Though he remained a student of Imām al-Khomeini for around ten-years, his ruling slightly differs from other contemporary scholars as he requires one to repeat their prayers:
سؤال 1454. آیا در غیر ایّام حج و در شرایط معمولی، شیعیان میتوانند به امام جماعت اهلسنّت اقتداکنند؟
میتوانند و اگر موجب اتّحاد شود، بسیار هم ثواب دارد، ولی به هر حال چه در حرمین شريفین باشند و چه در جاهای دیگر، بايد این نماز را اعاده کنند
Q 1454: In non-pilgrimage days and in normal conditions, can the Shī’a perform congregational prayers behind an Ahl al-Sunnah Imām?
A: They can, and if it results in unity, it has tremendous reward. However, in any case – whether they are in the two holy mosques or elsewhere – the prayer must be repeated.
Though this is not an exhaustive list of contemporary scholars, and many more opinions could have been cited, for the purpose of the paper, this amount suffices us.
From the rulings that have been gathered, a number of points can be derived and understood. First and foremost, what is understood from these rulings is that the discourse concerning praying behind a Sunnī falls under the discussion of dissimulation and the implementation of the principle of dissimulation. In other words, the primary ruling with respect to praying in congregation is that the Imām leading the prayers, must be a just Shi’ī Imāmī, which in our day and age refers to one who believes in the divine leadership of the twelve Imāms.
Given that a Sunnī does not meet the criterion for a Shī’ī to be able to pray behind them, all exceptions being made to the rule have to be legislated through a secondary ruling. In this context, this secondary ruling is legislated through the principle of dissimulation, which is further corroborated by the numerous traditions on this topic. Amongst the classical and pre-contemporary scholars, the general view had always been that the prayers being conducted behind a Sunnī Imām, is, in fact, an individual prayer, or a mere act. In other words, a Shī’ī could pray behind a Sunnī Imām while portraying themselves as praying in congregation, while in actuality they would be praying their own individual prayers without the intention of congregation.
In cases of intense dissimulation, when a person had, for example, already prayed their individual prayers, or that it was not even possible for a person to perform wuḍū or tayammum out of fear of being exposed, then such dissimulation would necessitate one to act out a prayer. This can be witnessed in the way Shaykh Aḥmad al-Qaṭīfī explains the ruling, where if one out of fear is not even able to perform the wuḍū as it would expose their jurisprudential school of thought, then simply pretending to pray behind them is required.
What seems to have significantly changed in the discussion of its permissibility, are the instances of dissimulation. While one will be hard-pressed to find any classical scholars discussing the permissibility of praying for the purpose of maintaining unity, later scholars began mentioning this as one of the instances where dissimulation applies. This is understandable given the socio-political climate under which these scholars lived. While fear was a significant factor amongst earlier scholars, as time progressed, discussion on fear became restricted more so to the pilgrimage season under the Saudi regime.
Nevertheless, the breaking up of an Islamic civilization into factions, and the discovery of nation-states in the 20th century due to imperialist conspiracies, would have been a significant factor amongst scholars to ensure the unity of the Muslims. This need can be felt in the words of Sayyid al-Mūsawī who lived in the middle of such a crisis. With the coming of Imām al-Khomeinī, who himself was a strong promoter of Islamic unity, the discussion concerning its permissibility shifted more towards unity rather than fear.
Another common opinion amongst majority of the jurists was that a prayer that was performed behind an Ahl al-Sunnah Imām does not need to be repeated. This verdict would have been given due to a discussion on one of the implications of the principle of dissimulation, which establishes the soundness of actions conducted while in a state of dissimulation. Thus repeating that which was permitted by the Legislator out of dissimulation is not required, unless stated otherwise.
A final matter concerns the intention of this prayer. Amongst the rulings of some of the jurists – specifically scholars before the 20th century – the matter is very clear. For many, the notion of praying in congregation behind them was in fact either a mere act, or the intention a person makes is of an individual prayer. This ruling definitely changed after the middle of the 20th century, and some have been explicit in stating that the intention one makes during this prayer is of congregation itself.
The verdict regarding congregational prayers behind an Ahl al-Sunnah Imām was consistently discussed by Shī’a jurists. While it was for many centuries a discussion that would take place within the context of practicing dissimulation due to fear, after the 20th century most jurists began discussing it through the lens of unity. Nevertheless, the permissibility of praying behind them has never been brought to question, even though historically this congregational prayer was in fact not more than a mere appearance and show of congregation. Since the middle of the last century, some jurists have gone a step further and have allowed praying in congregation behind them even with the intention of congregation.
 I.e. that I am an Imāmī
 Ibn Idrīs, Muḥammad bin Aḥmad (1410 AH). al-Sarā’ir al-Ḥāwi li-Taḥrīr al-Fatāwi, vol. 3, pg. 592. Qom: Mu’assaseh al-Nashr al-Islāmī al-Tabi’ah li-Jamā’ah al-Mudarrisīn
 Al-Kulaynī, Muḥammad bin Ya’qūb (1407 AH). Al-Kāfī, vol. 3, pg. 380. Tehran: Dār al-Kutub al-Islāmiyyah.
 Al-Ṣadūq, Ibn Bābuwayh Muḥammad bin ‘Alī (1413 AH). Man Lā Yaḥḍuruhu al-Faqīh, vol. 1, pg. 407. Qom: Mu’assaseh al-Nashr al-Islāmī al-Tabi’ah li-Jamā’ah al-Mudarrisīn
 Al-‘Urayḍī, ‘Alī bin Ja’far (1409 AH). Masā’il ‘Alī bin Ja’far wa Mustadrakātihā, pg. 144. Qom: Mu’assaseh Āl al-Bayt
 See for example: Bīnesh va Ravish Ijtihad dar Maktab-e Shaykh Anṣārī by Shaykh Mahdi Hadawi; and Āshnayī ba Fiqh Jawāhiri by Dr. Abdullah Umīdī Fard.
 Meaning, do not do the intention of congregation behind them.
 This is referring to the phrase ḥayya ‘ala khayr al-‘amal, and repeating some of the phrases twice in the iqāmah that the Ahl al-Sunnah drop.
 Al-Ṣadūq, Muḥammad ibn Bābuwayh. Man Lā Yaḥḍuruhū al-Faqīh, vol. 1, pg. 381.
 Al-Ṣadūq, Muḥammad ibn Bābuwayh. Man Lā Yaḥḍuruhū al-Faqīh, vol. 1, pg. 381.
 Al-Ṣadūq, Ibn Bābuwayh Muḥammad bin ‘Alī (1418 AH). Al-Hidāyah fi al-Uṣūl wa al-Furū’, pg. 147. Qom: Mu’assasah Imām al-Hādī.
 Al-Mufīd, Muḥammad bin Nu’mān (1413 AH). Al-Muqni’ah, pg. 164. Qom: Congreh Jahānī Hazāreh Shaykh Mufīd.
 Al-Ṭūṣī, Muḥammad bin Ḥasan (1400 AH). Al-Nihāyah fi Mujarrad al-Fiqh wa al-Fatawa, pg. 112. Beirut: Dār al-Kutub al-‘Arabī.
 Al-Ṭūṣī, Muḥammad bin Ḥasan (1387 AH). Al-Mabsūṭ fi Fiqh al-Imāmiyyah, vol. 1, pg. 158. Tehran: Al-Maktabah al-Murtaḍawiyyah li-iḥyā al-Āthār al-Ja’fariyyah.
 Ibn al-Barrāj (1407 AH). al-Muhadhdhab, vol. 1, pg. 81-82. Qom: Daftar-e Intishārāt.
 Ibn Idrīs, Muḥammad bin Aḥmad (1410 AH). al-Sarā’ir al-Ḥāwi li-Taḥrīr al-Fatāwi, vol. 1, pg. 284. Qom: Mu’assaseh al-Nashr al-Islāmī al-Tabi’ah li-Jamā’ah al-Mudarrisīn
 Muḥaqqiq al-Ḥillī, Ja’far bin Ḥasan (1418 AH). al-Mukhtaṣar al-Nāfi’ fi Fiqh al-Imāmiyyah, vol. 1, pg. 29. Qom: Mu’assasah al-Maṭbū’āt al-Dīnīyyah.
 Al-Ḥillī, Yaḥya bin Sa’īd (1405 AH). Al-Jāmi’ lil-Sharā’i, pg. 72-73. Qom: Mu’assasah Sayyid al-Shuhadā al-‘Ilmiyyah.
 ‘Allāmah Al-Ḥillī, Ḥasan bin Yūsuf (1420 AH). Taḥrīr al-Aḥkām al-Sharī’ah ‘ala Madhab al-Imāmiyyah, vol. 1, pg. 230. Qom: Mu’assasah Imām Ṣādiq.
 ‘Allāmah Al-Ḥillī, Ḥasan bin Yūsuf (1421 AH). Talkhīṣ al-Marām fi Ma’rifah al-Aḥkām, pg. 32. Qom: Intishār Daftar-e Tablīghāt.
 ‘Allāmah Al-Ḥillī, Ḥasan bin Yūsuf (1413 AH). Mukhtalaf al-Shi’a ila Aḥkām al-Sharī’ah, vol. 3, pg. 87. Qom: Intishār Daftar-e Tablīghāt.
 Al-Shahīd al-Awwal, Muḥammad bin Makkī (1412 AH). Al-Bayān, pg. 243. Qom: Muḥaqqiq; and Al-Shahīd al-Awwal, Muḥammad bin Makkī (1419 AH). Al-Dhikra al-Shi’a fi Aḥkām al-Sharī’ah, vol. 4, pg. 329. Qom: Mu’assasah Āl al-Bayt.
 Al-Shahīd al-Awwal, Muḥammad bin Makkī (1418 AH). Al-Durūs al-Sharī’ah fi Fiqh al-Imāmiyyah, vol. 1, pg. 224. Qom: Daftar-e Intishārāt-e Islāmī
 Al-Shahīd al-Thānī, Zayn al-Dīn (1421 AH). Rasā’il al-Shahīd al-Thānī, vol. 1, pg. 585. Qom: Intishārāt Daftar-e Tablīghāt Islāmī.
 The narration being referred to is the second tradition quoted in the section ‘Hadith Literature’
 Al-Majlisī, Muḥammad Taqī (1407 AH). Rawḍah al-Muttaqīn fī Sharḥ Man Lā Yaḥḍuruhu al-Faqīh, vol. 2, pg. 510. Qom: Mu’assasah Farhangi Islāmī Kūshānbūr.
 Al-Majlisī, Muḥammad Taqī (1414 AH). Lawāmi’ Ṣāḥibqurānī, vol. 4, pg. 410. Qom: Mu’assasah Ismā”īlīyān.
 Al-Māzandarānī, Muḥammad bin Muḥammad Ṣāleh (1429 AH). Sharḥ Furū’ al-Kāfī, vol. 3, pg. 298. Qom: Dār al-Ḥadīth.
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 Al-Baḥrānī, Yūsuf bin Aḥmad (1405 AH). Al-Ḥadāiq al-Nādirah fi Aḥkām al-‘Itrah al-Ṭāhirah, vol. 11, pg. 71. Qom: Daftar-e Intishārāt-e Islāmī.
 Kāshif al-Ghiṭā’, Ja’far bin Khiḍr (1422). Kashf al-Ghiṭā’ ‘an Mubhamāt al-Sharī’ah al-Gharrā’, vol. 3, pg. 312. Qom: Daftar-e Intishārāt-e Islāmī.
 Mīrza al-Qumi, Abū al-Qāsim bin Muḥammad (1417 AH). Ghanāim al-Ayyām fi Masāil al-Ḥalāl wa al-Ḥarām, vol. 3, pg. 158. Qom: Intishārāt-e Daftar-e Tabīghāt.
 Qur’ān 63:4
 Al-Qaṭīfī, Aḥmad bin Ṣālih (1422 AH). Rasā’il Āl Ṭuq al-Qaṭīfī, vol. 1, pg. 365 – 366. Beirut: Dār al-Muṣṭafa li-iḥyā al-Turāth.
 Al-Najafī, Muḥammad Ḥasan (1404 AH). Jawāhir al-Kalām fi Sharḥ Sharā’i al-Islām, Vol. 13, pg. 195. Beirut: Dār Iḥyā al-Turāth al-‘Arabī.
 Al-Anṣārī, Murtaḍa bin Muḥammad (1415 AH). Kitāb al-Ṣalāt, Vol. 2, Pg. 374. Qom: Congreh Jahānī Buzurgdṣht Shaykh ‘Aẓam Anṣārī.
 ibid, pg. 471
 ‘Adālah is generally understood to be a disposition where a person abstains from committing major sins, and does not persist on committing minor sins
 Sharaf al-Dīn al-Mūsawī, ‘Abd al-Ḥusayn (1377 AH). Ajwibah Masāil Jār Allah, pg. 87. Qom: Intishārāt Maktabah al-Faqīh.
 Khū’ī, Sayyid Abū al-Qāsim (1416 AH). Ṣirāṭ al-Najāt fī Ajwibah al-Istifta’āt, volume 1, pg. 101. Qom: Maktab Nashr al-Muntakhib.
 Ibid, pg. 101-102.
 Ibid, volume 3, pg. 76.
 Ibid, pg. 74.
 Ibid, pg. 74.
 Khomeinī, Rūh Allah (1392 SH). Istifta’at Imam Khomeini, vol. 3, pg. 344. Tehran: Mu’assasah Tanzīm wa Nashr Athār Imām Khomeini.
 Khomeinī, Rūh Allah (1392 SH). Istifta’at Imam Khomeini, vol. 3, pg. 352. Tehran: Mu’assasah Tanzīm wa Nashr Athār Imām Khomeini.
 Al-Sīstānī, Sayyid ‘Alī (1430 AH). Manāsik al-Ḥajj wa Mulhaqātuhā. <https://www.sistani.org/arabic/book/14/3596/>. Accessed January 3, 2018.
 Shirāzī, Makārem. Iqtidā beh Imām-e Jamā’at-e Ahl-e Sunnat dar Ghayr Kishwar-e ‘Arabistān. <https://makarem.ir/main.aspx?typeinfo=21&lid=0&catid=710&mid=216002>. Accessed January 3, 2018.
 Maẓāhirī, Ḥusayn. Risaleh Istifta’at, vol. 1. <http://almazaheri.org/Farsi/Index.aspx?TabID=0604&SectionNum=3938&ChapterNum=939&ChapterName=نماز&BookNum=165&BookName=رساله%20استفتائات-%20جلد%201&CompileNum=21&CompileName=فقه>. Accessed January 4, 2018.
 See page 18, ‘Post-Safavid Scholars’
 Al-Anṣārī, Murtaḍa bin Muḥammad (1412 AH). Al-Taqiyyah, pg. 43-44. Qom: Mu’assasah Qā’im Āl Muḥammad
Sayyid Ali Imran studied in the seminary of Qom from 2012 to 2021, while also concurrently obtaining a M.A in Islamic Studies from The Islamic College of London in the summer of 2018. He continued his seminary studies in legal theory, jurisprudence and philosophy, eventually attending the advanced kharij of Usul and Fiqh in 2018. He is also a regular instructor for Mizan Institute.