Musannaf Ibn Abi Shayba 1:1929

Yahya ibn Abi Bukayr narrated to us, he said: Shu'bah narrated to us, from Abu Bakr ibn Hafs, from Abu 'Abd Allah, the freed slave of At-Taym ibn Murrah, from Abu 'Abd al-Rahman, who said: I was sitting with 'Abd al-Rahman ibn 'Awf when Bilal passed by us. We asked him about wiping over the leather socks (khuffayn). He said: The Messenger of Allah (peace be upon him) would relieve himself, then come out, and we would bring him water. He would perform ablution and wipe over his leather socks and his turban.