Musannaf Ibn Abi Shaybah

Fudayl narrates from Ibrahim regarding the issue that if a man leaves behind his grandfather and real brother, then according to the statements of Ali, Abdullah, and Zaid (may Allah be pleased with them), both the grandfather and the brother will be entitled to half of the wealth each. And regarding the man who leaves behind his grandfather and two real brothers, these personalities state that the grandfather will receive one-third of the wealth and the brothers will receive two-thirds of the wealth. Abu Bakr (may Allah be pleased with him) states that this issue will be resolved in two parts: in the case where among the heirs there is a sister or brother and a grandfather, then the grandfather will receive half of the wealth, and the sister or brother will also receive half of the wealth. And if the heirs are two brothers instead of one, then the grandfather will receive one-third of the wealth and both brothers will receive two-thirds of the wealth.