Sayyiduna Abu Hurairah (may Allah be pleased with him) narrated from the Messenger of Allah (peace and blessings be upon him), he said: "A mortgaged animal may be ridden in exchange for its maintenance, and a milking animal, when it is mortgaged, its milk may be drunk in exchange for its maintenance. And whoever rides or drinks its milk, its maintenance is his responsibility."
Hadith Referenceمسند اسحاق بن راهويه / كتاب الرهن والاجارة / 470