Musannaf Ibn Abi Shayba 26:323

Hafs narrated to us, from Ash'ath, from Jahm, from Ibrahim, that Ali inherited three [people] who drowned in a ship, one from the other, while their mother was alive. So he gave their mother one-sixth from the estate of each one of them, then he gave her one-third of what each one of them inherited from his companion, and he assigned what remained to the agnatic heirs (*'asaba*).