Sunan An-Nasai, Chapter: The Book of Purification

that when the Messenger of Allah (saw) performed Ghusl from Janabah, the vessel (of water) would be placed before him, and he would pour water over his hands before putting them into the vessel. When he had washed his hands, he would put his right hand in the vessel then pour water with his right hand and wash his private parts with his left hand. Then he had finished, he would pour water with his right hand over his left hand and wash them both. Then he would rinse his mouth and nose three times, then he would pour water filling both of his hands over his head three times, then he would pour water over his body. (Hasan)