(19) باب السَّهْوِ فِي الصَّلاَةِ وَالسُّجُودِ لَهُ
'Abdullah (b. Mas'ud) reported:
The Messenger of Allah (ﷺ) led us five (rak'ahs in prayer). We said: Messenger of Allah, has the prayer been extended? He said: What is the matter? They said: You have said five (rak'ahs). He (the Holy Prophet) said: Verily I am a human being like you. I remember as you remember and I forget just as you forget. He then performed two prostrations as (compensation of) forgetfulness.
Reference: Sahih Muslim 572 k
In-book reference: Book 5, Hadith 122
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1178