Musnad Ahmad 5:612

Muhammad ibn Ja'far narrated to us, Hajjaj said: He said: Shu'bah narrated to me, he said: I heard Malik ibn 'Urfutah, he said: I heard 'Abd Khayr, he said: I saw 'Ali, a chair was brought to him, so he sat upon it. Then a pitcher—Hajjaj said: a basin—of water was brought to him. He said: "So he washed his hands three times, and rinsed his mouth three times along with sniffing water into the nose with one handful of water, and washed his face three times, and washed his forearms three times—Hajjaj said: three times, three times—with one hand. And he placed his hands into the basin, then he wiped his head—Hajjaj said: He gestured with his hands from the front of his head to the back of his head, he said: And I do not know if he returned them to the front of his head or not—and he washed his feet three times—Hajjaj said: three times, three times." Then he said: "Whoever wishes to look at the purification of the Messenger of Allah, may Allah bless him and grant him peace, then this is the purification of the Messenger of Allah, may Allah bless him and grant him peace."