Chapter on the Rulings of Congregational Prayer (the Minimum Number for Congregational Prayer, the Description of the Imam, Who Is to Be Followed and Who Is Not to Be Followed, Recitation Behind Both of Them, the Rulings of Those Led in Prayer, and Other Such Rulings Related to It)

Muhammad ibn Yaqub from Muhammad ibn Yahya from Ahmad ibn Muhammad from Uthman ibn Isa from Sama’ah, who said: I asked Imam عليه السلام about a man who had begun to pray, and the imam (of prayer) came out while the man had already prayed one rak’ah of the obligatory prayer. Imam عليه السلام said: “If the imam (of prayer) is just, then let him complete another rak’ah and end the prayer, and count it as a supererogatory (nafl) prayer, and then enter into prayer with the imam (of prayer). But if the imam (of prayer) is not just, then let him continue his own prayer as it is, and perform another rak’ah with the imam (of prayer), and remain seated for the duration it takes to say: ‘I bear witness that there is no God but Allah سبحانه وتعالى, alone with no partner, and I bear witness that Muhammad صلى الله عليه وعلى آله وسلم is His عز وجل servant and His عز وجل messenger’. Then let him complete his prayer with the imam (of prayer) to the best of his ability. Indeed, taqiyyah is expansive, and there is no act of taqiyyah except that the one who performs it is rewarded for it, if Allah سبحانه وتعالى wills.”