Sunan Ibn Majah Book 1, Hadith 125
"I poured water for the Prophet on journeys and as a resident, when he performed ablution."
"I brought a basin of water to the Prophet and he said: 'Pour it,' so I poured it and he washed his face and forearms, then he took fresh water and wiped his head, front and back, and then he washed his feet. He washed each part three times."
"I used to help the Messenger of Allah perform ablution, when I was standing and he was sitting."