Sahih Muslim
The Book of Transactions (Kitab Al-Buyu)
Book Number: 010 / Hadith Number: 3616
Ibn 'Umar (Allah be pleased with them) reported that the people of pre-Islamic days used to sell the meat of the slaughtered camel up to habal al-habala. And habal al-habala implies that a she-camel should give birth and then the (born one should grow young) and become pregnant. Allah's Messenger (may peace be upon him) forbade them that (this transaction).