The Messenger of Allah ﷺ said: If any one of you offers prayer and feels a movement between his paddocks, but is doubtful whether or not his ablution broke, he should not cease praying unless he hears a sound or perceives a smell. (Using translation from Abū Dāʾūd 177)   

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ «إِذَا وَجَدَ أَحَدُكُمْ فِي صَلَاتِهِ حَرَكَةً فِي دُبُرِهِ فَأَشْكَلَ عَلَيْهِ أَحْدَثَ أَوْ لَمْ يُحْدِثْ فَلَا يَنْصَرِفَنَّ حَتَّى يَسْمَعَ صَوْتًا أَوْ يَجِدَ رِيحًا»