(25) باب التَّحَرِّي
It was narrated that 'Abdullah said:
"Whoever has doubt, or is not sure, let him estimate what is correct, then let him prostrate twice." (ID)
Reference (ID): Sunan an-Nasa'i 1246 (ID)
In-book reference (ID): Book 13, Hadith 68 (ID)
English translation (ID): Vol. 2, Book 13, Hadith 1247 (ID)