Musannaf Ibn Abi Shayba 1:1063

Abu al-Ahwas narrated to us, from Abu Ishaq, from Abu Hayyah, who said: I saw Ali perform ablution. He cleaned his palms, then he washed his face and his forearms. Then he said: "I only intended to show you the purification of the Messenger of Allah, may Allah bless him and grant him peace."