Musannaf Ibn Abi Shayba 26:59

Waki’ narrated to us, from Shu’bah, from Aws, from Hakim ibn ‘Iqal, who said: Ali was approached regarding two cousins, one of them a husband and the other a maternal brother. He said to Shurayh: "Decide regarding them." Shurayh said to the husband: "The half, and whatever remains is for the brother." Ali said to him: "Is that your opinion?" He said: "That is how I see it." So Ali gave the husband the half and the brother the sixth, and he divided what remained between them.