‘Abdullāh reported that a complaint was made to the Prophet (may Allah’s peace and blessings be upon him) about the person who doubts that something (breaking his ablution) has happened to him during his prayer, and he said: "He should not leave (his prayer) unless he hears a sound or perceives a smell." [Al-Bukhari]

"عن عبد الله بن زيد بن عاصم المازني -رضي الله عنه- قال: (شُكِيَ إلى النبيِّ -صلى الله عليه وسلم- الرَّجلُ يُخَيَّلُ إِليه أنَّه يَجِد الشَّيء في الصَّلاة، فقال: لا ينصرف حتَّى يَسمعَ صَوتًا، أو يَجِد رِيحًا). [صحيح.] - [متفق عليه.]