Musannaf Ibn Abi Shayba 26:60

Yahya ibn Zakariyya ibn Abi Za'ida narrated to us, from Isra'il, from Mansur, from Ibrahim, regarding a woman who left behind three paternal cousins, one of whom was her husband and another was her brother through her mother. Ali and Zayd said: "The husband gets half, the brother through the mother gets one-sixth, and what remains is [divided] between them equally." Ibn Mas'ud said: "The husband gets half, and what remains is for the brother through the mother." Abu Bakr said: "According to the opinion of Ali and Zayd, this is out of six shares: the husband gets half, which is three [shares], and the brother through the mother gets one-sixth, and two shares remain, which are between them. According to the opinion of Ibn Mas'ud, it is out of two shares: the husband gets half, and what remains is for the brother through the mother."