Musnad Ahmad 33:1105

Husayn narrated to us, Sharik narrated to us, from al-Mughirah, from ‘Amir, from Jabir ibn ‘Abdullah, who said: "The Prophet, peace and blessings of Allah be upon him, bought a camel from me, on the condition that I be allowed to ride its back for his journey—or for that journey of mine—then he gave me the camel and the price."