Sahih al-Bukhari 137
Sahih al-Bukhari · Book 4: Ablutions (Wudu') · One should not repeat ablution if in doubt unless and until he is convinced (that he has lost his ablution by having Hadath)
Narrated `Abbad bin Tamim:
حَدَّثَنَا عَلِيٌّ ، قَالَ حَدَّثَنَا سُفْيَانُ ، قَالَ حَدَّثَنَا الزُّهْرِيُّ ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ ، وَعَنْ عَبَّادِ بْنِ تَمِيمٍ ، عَنْ عَمِّهِ ، أَنَّهُ شَكَا إِلَى رَسُولِ اللَّهِ صلى الله عليه وسلم الرَّجُلُ الَّذِي يُخَيَّلُ إِلَيْهِ أَنَّهُ يَجِدُ الشَّىْءَ فِي الصَّلاَةِ. فَقَالَ " لاَ يَنْفَتِلْ ـ أَوْ لاَ يَنْصَرِفْ ـ حَتَّى يَسْمَعَ صَوْتًا أَوْ يَجِدَ رِيحًا " .
My uncle asked Allah's Messenger (ﷺ) about a person who imagined to have passed wind during the prayer. Allah' Apostle replied: "He should not leave his prayers unless he hears sound or smells something."