Sa’ad from Abu Ja’far, from Muhammad ibn Abi Umayr, from Hammad ibn Uthman, from Ubaydullah al-Halabi, from Abu Abdillah عليه السلام, peace be upon him, who said: Imam al-Sadiq عليه السلام said: “If you have prayed a prayer while you are in the mosque and the congregational prayer is established, then if you wish, you may leave, and if you wish, pray with them and make it tasbih (supererogatory prayer).”