Musannaf Ibn Abi Shayba 1:1943

Mukhlad ibn Yazid—and he was trustworthy—narrated to us, from Sa’id ibn ‘Abd al-‘Aziz, who said: I asked al-Zuhri about wiping over the leather socks (khuffayn). He gestured with his hand like this, and he passed his fingers from the front of his foot to its top.