Musannaf Ibn Abi Shayba 35:416

Zayd ibn al-Hubab narrated to us, from Umar ibn Sulayman al-Bahili, from Abu Ghalib, who said: I saw Abu Umamah perform ablution three times [for each part], and he combed his beard with his fingers, and he said: I saw the Messenger of Allah, may Allah bless him and grant him peace, do it.