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." (DE)
English reference (DE): Vol. 1, Book 1, Hadith 516 (DE)
Arabic reference (DE): Book 1, Hadith 556 (DE)