Musannaf Ibn Abi Shayba 35:106

Waki’ narrated to us, from Zakariya, from ‘Amir, from Abu Hurayrah, who said: The Prophet (peace and blessings of Allah be upon him) said: "The back (of the animal) is to be ridden if it is pledged as collateral, and the milk of the nursing animal is to be drunk if it is pledged as collateral. And upon the one who rides and drinks is its maintenance."