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 Husayn ibn ‘Uthman, from Sama‘ah, from Abu Basir, who said: I asked Him عليه السلام about a man who forgets to recite the tashahhud. Imam عليه السلام said: "He should perform two prostrations (sajdatay al-sahw) in which he recites the tashahhud."