Sahih Bukhari Volume 1, Book 5, Hadith Number 279

Narated By Maimuna : I screened the Prophet while he was taking a bath of Janaba. He washed his hands, poured water from his right hand over his left and washed his private parts. Then he rubbed his hand over a wall or the earth, and performed ablution similar to that for the prayer but did not wash his feet. Then he poured water over his body, shifted from that place, and washed his feet.