It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the people of the Age of Ignorance used to sell the meat of a camel in exchange for the fetus of another camel, and the explanation of the trade of the fetus of the fetus is that a she-camel would give birth to the young in her womb, then when that offspring would become pregnant and give birth to a male or female, (they would sell the meat along with that). The Messenger of Allah (peace and blessings be upon him) forbade people from this.