Musannaf Ibn Abi Shayba 26:55

Jarir narrated to us, from Mughira, from al-Sha'bi, who said: Ali and Zayd used to say regarding the sons of a paternal uncle: If one of them is a maternal brother, they would give him one-sixth, and what remained would be between him and the sons of the paternal uncle. And Abdullah used to give him the entire wealth.