Musnad Ahmad 952:0

Narrated to us by Muhammad ibn Ja'far, who said: Narrated to us Shu'bah, from 'Amr ibn Murrah, who said: I heard Murrah al-Hamadani narrating from 'Umayr, the freed slave of Abi al-Lahm, that he witnessed the Messenger of Allah (ﷺ) while he was slaughtering [an animal] at al-Marwah. He said: And he [the Prophet] commanded me, so I slaughtered it. He said: And he [the Prophet] commanded me to distribute its meat, so I distributed it. He said: And he [the Prophet] passed by me while I was eating a piece of meat, and he said: "O 'Umayr, give me some of it." So I gave him a piece, and he ate it.