Musnad Ahmad 2:6

Qutaybah ibn Sa'id narrated to us, Ibn Lahi'ah narrated to us, from Abu al-Nadr, from Abu Salamah, from Ibn Umar, that he said: I saw Sa'd ibn Abi Waqqas wiping over his leather socks in Iraq when he performed ablution, so I disapproved of that regarding him. He said: When we gathered at Umar ibn al-Khattab’s, he said to me: "Ask your father about what you disapproved of regarding me concerning the wiping over the leather socks." He said: So I mentioned that to him, and he said: "If Sa'd narrates something to you, do not reject it, for the Messenger of Allah, peace and blessings of Allah be upon him, used to wipe over the leather socks."