It was narrated that 'Amr bin 'Ata' said:
"I saw Sa'ib bin Yazid sniffing his garment, and I said: 'Why (are you doing) that?' He said: 'I heard the Messenger of Allah say: "No ablution (is needed) unless there is an odor or a sound." (JA)
English reference (JA): Vol. 1, Book 1, Hadith 516 (JA)
Arabic reference (JA): Book 1, Hadith 556 (JA)