Sahih Bukhari
Ablutions (Wudu)
Volume: 001 / Book Number: 004 / Hadith Number: 205
Narrated 'Urwa bin Al-Mughira:
My father said, "Once I was in the company of the Prophet on a journey and I dashed to take off his Khuffs. He ordered me to leave them as he had put them after performing ablution. So he passed wet hands or them.