Musnad Ahmad 33:139

Hushaym narrated to us, Sayyar informed us, from Abu Hubayrah, from Jabir ibn Abdullah, who said: We were with the Messenger of Allah, peace and blessings of Allah be upon him, on a journey. He bought a camel from me and granted me its back [to ride] until I reached Medina. When I arrived, I came to him with the camel and handed it over to him. He ordered that I be paid the price, and then I departed. Suddenly, the Messenger of Allah, peace and blessings of Allah be upon him, caught up with me. I said: Perhaps he has changed his mind. He said: When I came to him, he handed the camel back to me and said: "It is yours." I passed by a man from the Jews and informed him. He began to marvel and said: He bought the camel from you, paid you the price, and then gifted it to you? I said: "Yes."