Musnad Ahmad 1077:10

Yazid ibn Abd Rabbih narrated to us, Muhammad ibn Harb narrated to us, al-Zubaydi narrated to me, from al-Zuhri, from Abdullah ibn Thalaba ibn Su'ayr al-Udhri, who said: "And the Messenger of Allah, may Allah bless him and grant him peace, had wiped his face during the time of the Conquest."