Musannaf Ibn Abi Shayba 13:3278

Abu Bakr narrated to us, he said: Jarir narrated to us, from Mughira, from Ibrahim, who said: "There is no profit for wealth that is guaranteed." He said: Its interpretation is a man taking wealth from a man as *mudaraba* (profit-sharing partnership) and saying, "I guarantee it for you, and you shall have half of the profit, or a third."