This is a letter written by Imam Hasan al-Askari (as) to the father of Sheikh Saduq, Ali ibn Husayn ibn Musa ibn Babwayh al-Qummi; quoted in the book Rawdhat al-Jannat, volume 4. He was a prominent Shi’a figure of his time. The English translation is taken from the translation of the book Life of Imam al-Hasan al-Askari by Baqir Shareef.
“Praise be to Allah the Lord of the worlds, and the end is for the righteous, the Paradise is for the monotheists, the Hell is for the atheists, and there should be no hostility except against oppressors, and there is no god but Allah the best of creators, and blessing be on the best of His creation Muhammad and his pure progeny.
O my sheikh, trustee, jurisprudent Abul Hasan Ali bin al-Husayn al-Qummi-may Allah be satisfied with you, and make from your progeny good children- I recommend you to fear Allah, offer prayers, and give zakat because no prayer is accepted from one who does not give zakat. I also recommend you to pardon others, suppress anger, continuously associate with kin, comfort brothers and try to carry out their needs at difficulty and ease, be patient, learn religion, be certain of things, undertake the Qur’an, behave with good morals, enjoin the good, and to forbid the wrong. Allah says, (There is no good in most of their secret counsels except (in his) who enjoins charity or goodness or reconciliation between people).
I recommend you to avoid all sins and vices. You are to keep on offering Night Prayer, for the Prophet (pbuh) had recommended Ali saying to him, ‘O Ali, you are to keep on the Night Prayer.’ He repeated that three times. Whoever disregards the Night Prayer is not from us. Act according to my recommendation and order my Shia to act due to that. Wait for deliverance, for the Prophet (pbuh) said, ‘The best deed of my nation is the waiting for deliverance.’ Our Shia shall be still in sorrow until my son, whom the Prophet (pbuh) brought good news about, shall appear. He will fill the earth with justice and fairness after it has been filled with injustice and oppression. O my sheikh, be patient and order all my Shia to be patient; (Surely the earth is Allah’s. He gives it as inheritance to whom He will and the end is (best) for the righteous).
Peace, mercy, and blessings of Allah be on you and on all our Shia, and Allah is sufficient for us; the best Protector is He, the best Patron, and the best Helper.”