كتاب السهو
13  
The Book of Forgetfulness (In Prayer)
(25)
Chapter: Estimating (what is most likely the case)
(25)
باب التَّحَرِّي
Sunan an-Nasa'i 1247
It was narrated that Ibrahim said:
"They used to say: 'If one is not sure of what he estimates is correct, then prostrate twice.'"
أَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ، قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ، عَنِ ابْنِ عَوْنٍ، عَنْ إِبْرَاهِيمَ، قَالَ كَانُوا يَقُولُونَ إِذَا أَوْهَمَ يَتَحَرَّى الصَّوَابَ ثُمَّ يَسْجُدُ سَجْدَتَيْنِ ‏.‏
Grade: Sahih (Darussalam)
Reference : Sunan an-Nasa'i 1247
In-book reference : Book 13, Hadith 69
English translation : Vol. 2, Book 13, Hadith 1248