Musannaf Ibn Abi Shaybah 21732 — Selling with uncertainty (gharar)

Sayyiduna Abu Sa'id (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) forbade the buying and selling of the young in the bellies of animals until they are born; likewise he forbade the buying and selling of milk in the udders until it is drawn and measured; and the sale of a runaway slave; and the sale of the spoils of war until they are divided; and buying things received as zakah until they are taken into possession. He also forbade making an agreement with a diver in the sea that he will dive and give the buyer whatever he finds.