عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ قَالَ: ((إِذَا وَجَدَ أَحَدُكُمْ فِي صَلَاتِهِ حَرْكَةً فِي دُبُرِهِ فَأَشْكَلَ عَلَيْهِ أَحْدَثَ أَوْ لَمْ يُحْدِثْ فَلَا يَنْصَرِفْ حَتَّى يَسْمَعَ صَوْتًا أَوْ يَجِدَ رِيحًا))
It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him and his family) said: When any one of you feels some movement in his backside, due to which he becomes uncertain whether he has broken his ablution or not, then in such a case he should not go (to perform ablution) until he hears a sound or perceives a smell.