Musnad Ahmad 33:786

'Affan narrated to us, Hammad ibn Salamah narrated to us, 'Ali ibn Zayd informed us, from Abu al-Mutawakkil, from Jabir ibn 'Abdullah, that the Messenger of Allah (may Allah bless him and grant him peace) passed by Jabir during the expedition of Tabuk. He said: "My camel had become exhausted." He said: "What is the matter with you, O Jabir?" I said: "My camel has collapsed." He said: So he came to it from behind its rear—and 'Affan said: "Its rear and its back are the same"—and he prayed and urged it on. He said: It did not cease to move ahead of the camels. He said: Then he came upon me and said: "What has the camel done?" I said: "It has not ceased to move ahead of them." He said: "For how much did you buy it?" I said: "For thirteen dinars." He said: "Then sell it to me for that price, and you shall have its back [the right to ride it] until Medina." I said: "Yes." He said: So when I arrived in Medina, I brought it by its halter, then I brought it to the Prophet (may Allah bless him and grant him peace), and he gave me the price and gave me back the camel.