(25) باب التَّحَرِّي
It was narrated that Ibrahim said:
"They used to say: 'If one is not sure of what he estimates is correct, then prostrate twice.'" (PT)
Reference (PT): Sunan an-Nasa'i 1247 (PT)
In-book reference (PT): Book 13, Hadith 69 (PT)
English translation (PT): Vol. 2, Book 13, Hadith 1248 (PT)