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 1246
It was narrated that 'Abdullah said:
"Whoever has doubt, or is not sure, let him estimate what is correct, then let him prostrate twice."
أَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ، قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ، عَنْ مِسْعَرٍ، عَنِ الْحَكَمِ، عَنْ أَبِي وَائِلٍ، عَنْ عَبْدِ اللَّهِ، قَالَ مَنْ شَكَّ أَوْ أَوْهَمَ فَلْيَتَحَرَّ الصَّوَابَ ثُمَّ لْيَسْجُدْ سَجْدَتَيْنِ ‏.‏
Grade: Sahih (Darussalam)
Reference : Sunan an-Nasa'i 1246
In-book reference : Book 13, Hadith 68
English translation : Vol. 2, Book 13, Hadith 1247