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

And from him, from Fadalah, from al-‘Ala’, from Ibn Abi Ya‘fur, who said: I asked Abu Abdillah عليه السلام, peace be upon him, about a man who performs the two rak‘ahs of the obligatory prayer and does not sit in them until he bows (in the third rak‘ah). Imam عليه السلام said: "He should complete his prayer, then give the salam, and perform the two prostrations of forgetfulness (sajdatay al-sahw) while he is seated, before he speaks."