Chapter on the Virtue of Mosques and Prayer Within Them, and the Virtue of Congregational Prayer and Its Rulings

And with this chain of transmission, from Abu Bakr who said: I said to Imam al-Sadiq عليه السلام: “I lead a group in prayer.” Imam عليه السلام said, “You give one taslim and do not turn your head. Say: ‘Peace be upon you, O’ Prophet, and the mercy of Allah سبحانه وتعالى and His blessings. Peace be upon you all.’ And do not recite anything from ‘Alif Lam Mim Ha Mim’ in the dawn (Fajr) prayer.” (meaning Huroof al-Muqatta'at that appear at the beginning of 29 Surahs of the Quran)