Sunan an-Nasa'i — The Book of Purification — Hadith No: 92
Translation
It was narrated that 'Abd Khair said:"We came to 'Ali bin Abi Talib, may Allah be pleased with him, and he had prayed. He called for water and we said: 'What is he going to do with it when he has (already) prayed? He only wants to teach us.' A vessel of water and a basin were brought to him. He poured some water onto his hand and washed it three times, then he rinsed his mouth and nose three times from the hand with which he took the water. Then he washed his face three times, and he washed his right hand three times, and his left hand three times, and wiped his head once, then he washed his right foot three times and his left foot three times. Then he said: 'Whoever would like to learn how the Messenger of Allah (ﷺ) did Wudu', this is it