Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "A riding animal may be ridden in return for its upkeep when it is pledged, and the milk of a she-camel may be drunk when she is pledged, and the upkeep is due from the one who drinks and rides."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرهن / 11205