Nafi' narrates from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the people of the Jahiliyyah used to sell camels (with payment due) up to habal al-habalah, and habal al-habalah is that the she-camel gives birth, and then the offspring that was born becomes pregnant; so the Messenger of Allah (peace and blessings be upon him) forbade that.
(b) Yahya bin Sa'id mentions something similar, (saying) that they used to sell the meat of camels.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10862