Abdullah (b. Mas'ud) reported:
The Messenger of Allah ( صلی اللہ علیہ وسلم ) said prayer and he omitted or committed (something). Ibrahim (one of the narrators of this hadith) said: It is my doubt, and it was said: Messenger of Allah, has there been any addition to the prayer? He (the Holy Prophet) said: Verily I am a human being like you. I forget just as you forget so when any one of you forgets, he must perform two prostrations, and he (the Holy Prophet) was sitting and then the Messenger of Allah ( صلی اللہ علیہ وسلم ) turned (his face towards the Qibla) and performed two prostrations.