It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Ablution is only required because of a sound or a smell."
(b) Arguing from this hadith, or from the narration of Sayyiduna Abu Sa'id (may Allah be pleased with him), in this matter is not valid.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1052