Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) says that the Prophet (peace and blessings be upon him) "forbade the sale of a stud's mating," and Ubaydullah added: "and the miller's qafiz (qafiz is a measure)."
(b) Waki' (may Allah have mercy on him) says: "He forbade hiring out a stud animal for mating."
(c) Abd al-Rahman bin Abi Nu'm (may Allah have mercy on him) says that the Messenger of Allah (peace and blessings be upon him) "forbade (it)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10854