Musnad Ahmad 30:2857

Abdullah ibn al-Walid and Mu’ammal narrated to us, they said: Sufyan narrated to us, he said: Abu al-Zinad narrated to me, from Musa ibn Abi Uthman, from his father, from Abu Hurairah, who said: The Messenger of Allah, peace and blessings of Allah be upon him, passed by a man driving a sacrificial camel. He said: "Ride it." He said: "O Messenger of Allah, it is a sacrificial camel." He said: "Ride it."