(25) باب التَّحَرِّي
It was narrated that 'Abdullah said:
"The Messenger of Allah (ﷺ) prayed and did more or less (rak'ahs). When he had said the taslim, it was said: 'O Messenger of Allah, has there been some change concerning the prayer?' He said: 'If there had been some change concerning the prayer, I would have told you. Rather I am a human being and I forget as you forget. If any one of you is not sure about his prayer, let him consider an estimate of what is correct, and complete his prayer on that basis, then say the taslim and prostrate twice.'"
Reference: Sunan an-Nasa'i 1242
In-book reference: Book 13, Hadith 64
English translation: Vol. 2, Book 13, Hadith 1243