Sayyiduna Jabir (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) said: "There is no owner of camels, nor of sheep, nor of cattle, who does not fulfil their due, except that he will be made to sit for them on the Day of Resurrection on a level plain. Those with hooves will trample him with their hooves, and those with horns will butt him with their horns. On that day there will be no animal among them without horns, nor one with a broken horn." We said: "O Messenger of Allah (peace and blessings be upon him), what is their due?" He (peace and blessings be upon him) said: "Lending its stud (for mating), lending its bucket, lending it as a milch animal, milking it at the water, and giving a ride on it in the path of Allah. And there is no owner of wealth who does not pay its zakah except that on the Day of Resurrection it will be turned into a huge bald serpent which will follow its wealthy owner wherever he goes while he flees from it, and it will be said to him: This is your wealth over which you used to be miserly. When he sees that there is no escape from it, he will put his hand into its mouth, and it will begin to gnaw it as a stallion chews."
Abu al-Zubayr (may Allah have mercy on him) said: I heard Ubayd bin Umayr (may Allah have mercy on him) say that a man said: "What is the due of camels?" He (peace and blessings be upon him) said: "Milking them at the water, lending their bucket, lending their stud, lending them as milch animals, and giving a ride on them in the path of Allah."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7785