It wasnarrated that 'Abdullah said:
"The Messenger of Allah (ﷺ)prayed, and he added or omitted something." (One of the narrators)Ibrahim said: "The confusion stems from me (i.e., he was not surewhich it was)." "It was said to him: 'O Messenger of Allah! Hassomething been added to the prayer?' He said: 'I am only human, Iforget just as you forget. If anyone forgets, let him perform twoprostrations when he is sitting (at the end).' Then the Prophet(ﷺ)turned and prostrated twice."
English reference: Vol. 1, Book 5, Hadith 1203
Arabic reference: Book 5, Hadith 1260