Musannaf Ibn Abi Shayba 1:54

Abu al-Ahwas narrated to us, from Abu Ishaq, from Abu Hayyah, who said: I saw Ali perform ablution. He cleaned his palms, then washed his face three times, and his forearms three times, and wiped his head, then washed his feet up to the ankles. Then he stood up and drank the remainder of his ablution water, then said: "I only wanted to show you the purification of the Messenger of Allah, may Allah bless him and grant him peace."