Musnad Ahmad 20:4

Yahya narrated to us, Mis'ar narrated to us, a sheikh from [the tribe of] Fahm narrated to me, and he said: "I think he was called Muhammad ibn Abd al-Rahman," and he said: "And I think he was a Hijazi," that he heard Abdullah ibn Ja'far narrating to Ibn al-Zubayr—while a camel had been slaughtered for the people—that he heard the Messenger of Allah (peace and blessings of Allah be upon him), while the people were offering meat to the Messenger of Allah (peace and blessings of Allah be upon him), saying: "The best of meat is the meat of the back."