Sunan an-Nasa'i #1247 · The Book of Forgetfulness (In Prayer)

Sunan an-Nasa'iIt was narrated that Ibrahim said
Sunan an-Nasa'i · Book 13 · The Book of Forgetfulness (In Prayer)
Sunan an-Nasa'i · كتاب 13 · كتاب السهو
"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 ‏.‏
Reference : Sunan an-Nasa'i 1247In-book reference : Book 13, Hadith 69