It is narrated from Sayyiduna Abdullah bin Zaid (may Allah be pleased with him) that he complained to the Messenger of Allah (peace and blessings be upon him) that during prayer he experiences something (which breaks wudu) and he begins to think that something has actually happened. The Prophet (peace and blessings be upon him) said: In such a situation, he should not leave the prayer until he perceives a smell or hears a sound.