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

Sa'd, from Ahmad ibn Muhammad, from his father, from Abdullah ibn al-Mughira, from Isma'il ibn Jabir: Abu Abdillah عليه السلام, peace be upon him, (was asked) regarding a man who forgot to perform the second prostration until he stood up, then while standing he remembered that he had not prostrated. Imam عليه السلام said: "Then let him perform the prostration, as long as he has not yet bowed (for ruku’). But if he rises and then remembers after his ruku’ that he did not prostrate, then let him proceed with his prayer until he completes it with the salam, then he should perform the prostration, for it is a makeup (qadahʾ)." And he (narrator) said: “Abu Abdillah عليه السلام, peace be upon him, said: "If he doubts regarding the ruku’ after having prostrated, then let him proceed. And if he doubts regarding the prostration after having stood up, then let him proceed. Everything in which there is doubt, after it has passed and one has entered into something else, then let him continue with it."