Musnad Ahmad 478:1

Ya'qub narrated to us, he said: My father narrated to us, from Ibn Ishaq, he said: Ja'far ibn 'Amr ibn Ja'far ibn 'Amr ibn Umayyah al-Damri narrated to me, from Abu Salamah ibn 'Abd al-Rahman, from Ja'far ibn 'Amr ibn Umayyah, from his father, he said: "I saw the Messenger of Allah, may Allah bless him and grant him peace, wiping over the khuffayn (leather socks)."