Sayyiduna Abdullah bin Umar (may Allah be pleased with them) narrated that the Messenger of Allah (peace and blessings be upon him) forbade the sale of the unborn offspring of a pregnant animal. This type of sale was prevalent in the days of ignorance. A person would buy a camel or a she-camel and set the payment term as follows: when a she-camel gives birth, and then the offspring in her womb grows up and gives birth.