Musnad Ahmad 1153:1265

Husayn ibn Ali narrated to us, from Za'idah, from 'Ata' ibn al-Sa'ib, who said: Abu Salamah ibn 'Abd al-Rahman ibn 'Awf narrated to me, from 'Aishah, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) would be in a state of major ritual impurity (janabah), so a vessel containing water would be placed for him. He would pour [water] over his hands and wash them before inserting them into the water. Then he would insert his right hand into the vessel and pour with it over his left hand, and wash his private parts. Then he would rinse his mouth and sniff water into his nose three times, and wash his face and his forearms. Then he would scoop three handfuls [of water] and pour them over his head, then he would wash the rest of his body."