Chapter on the Detailed Explanation of Prayer, Including the Obligatory and Recommended, and What is Permissible and Not Permissible.

Sa'd, from Muhammad ibn al-Husayn, from Ja‘far ibn Bashir, from Hammad ibn Uthman, from Abdullah ibn Abi Ya‘fur, from Abu Abdillah عليه السلام, peace be upon him, who said: I asked Him عليه السلام about a man who performs two rak‘ahs of the obligatory prayer and does not sit in them. Imam عليه السلام said: "If he remembers while he is standing in the third (rak‘ah), let him sit. But if he does not remember until he bows, then let him complete his prayer, and then perform two prostrations (sajdatay al-sahw) while he is seated, before he speaks."