Hadith 176
Abbad bin Tamim reported from his uncle that a person made a complaint to the Prophet ﷺ that he entertained (doubt) as if something had happened to him which had rendered his ablution invalid. He (the Prophet) said: He should not cease (to pray) unless he hears a sound or perceives a smell (of passing wind).
Hadith 177
Abu Hurairah said: 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.