Sahih Bukhari
Ablutions (Wudu)
Volume: 001 / Book Number: 004 / Hadith Number: 182
Narrated Al-Mughira bin Shu'ba:
I was in the company of Allah's Apostle on one of the journeys and he went out to answer the call of nature (and after he finished) I poured water and he performed ablution; he washed his face, forearms and passed his wet hand over his head and over the two Khuff, (leather socks).