Sunan An-Nasai, Chapter: The Book of Ghusl and Tayammum

from Aishah, and, from Amr bin Sa'd, from Nafi, from Ibn Umar: That Umar asked the Messenger of Allah (saw) about Ghusl from Janabah - and the narrations agree on this - that one should start by pouring water on the right hand two or three times, then put the right hand into the vessel and pour water with it onto the private parts, with the left hand on the private parts to wash off whatever is there, until it is clean; then put the left hand on the dust if one wants to, then pour water over the left hand until it is clean; then wash the hands three times, (sniff water into the nose) and rinse the mouth, and wash the face and forearms, three times each until when reaching the head, he does not wipe the head, rather he pours water over it. This is how the Messenger of Allah (saw) performed Ghusl according to what was mentioned. (Sahih)