Musannaf Ibn Abi Shayba 35:462

Yahya ibn Zakariyya narrated to us, from Zakariyya, from al-Sha'bi, from Jabir, who said: "I sold it to him for an uqiyya, and I stipulated the condition of riding it to my family. When I reached Medina, I came to him, and he paid me in full and said: 'Do you think I only bargained with you to take your camel and your wealth? They are both yours.'" And they mentioned that Abu Hanifa did not view it as permissible.