Musannaf Ibn Abi Shayba 13:913

Abu Bakr narrated to us, he said: Muhammad ibn Bakr narrated to us, from Ibn Jurayj, who said: I said to ‘Ata’: "I wrote a contract upon two men: that your living one is over your dead one, and your wealthy one is over your destitute one." He said: "It is permissible." And ‘Amr ibn Dinar and Sulayman ibn Musa said the same.