Musnad Ahmad 626:95

Ibrahim ibn Abi al-Abbas narrated to us, Abd al-Rahman ibn Abi al-Zinad narrated to us, from Abu al-Zinad, from Urwah, who said: Al-Mughirah ibn Shu'bah said: "I saw the Messenger of Allah, may Allah bless him and grant him peace, wiping over the tops of the khuffs (leather socks)." Surayj and al-Hashimi also narrated it to us.