Sahih Bukhari
Ablutions (Wudu)
Volume: 001 / Book Number: 004 / Hadith Number: 145
Narrated Ibn 'Abbas:
Once the Prophet entered a lavatory and I placed water for his ablution. He asked, "Who placed it?" He was informed accordingly and so he said, "O Allah! Make him (Ibn 'Abbas) a learned scholar in religion (Islam)."