(25) باب التَّحَرِّي
It was narrated that 'Abdullah said:
"The Messenger of Allah (ﷺ) said: 'If one of you is not sure about his prayer, let him estimate and prostrate twice after he has finished." (ID)
Reference (ID): Sunan an-Nasa'i 1241 (ID)
In-book reference (ID): Book 13, Hadith 63 (ID)
English translation (ID): Vol. 2, Book 13, Hadith 1242 (ID)