[Quran 6:119]. And He, Glorified and Exalted is He, says:
“And We have sent down to you the Book as a clear explanation of all things.” [Quran 16:89]
If Allah, Exalted is He, mentioned the three—and only three—cases concerning the mother, how could He fail to mention the five cases concerning the grandfather?! This is among the strongest proofs of the weakness of this view. The correct position, then, is that the grandfather takes the place of the father. He differs from the father in only one issue: the two Umariyyat cases, in which he is not treated as the father.
Thus, if the heirs are a wife, a mother, and a grandfather, the wife receives one-quarter, the mother one-third, and the remainder goes to the grandfather. If the heirs are a husband, a mother, and a grandfather, the husband receives one-half, the mother one-third, and the remainder goes to the grandfather. In these cases, the grandfather differs from the father and is not treated as the father. The distinction is clear: the grandfather is more remote in degree than the mother, and the more remote relative cannot compete with the nearer one. So we give the mother her full prescribed share and say that the grandfather receives what remains. This is unlike the case of the mother with the father, for they are equal in degree.
His statement: “The paternal grandfather, however remote, together with a child of both parents or of the father.” The maternal brother is excluded by the grandfather; this is why he said, “with a child of both parents or of the father.” A child of both parents is a full brother, while a child of the father is a paternal half-brother.
His statement: “like one of them.” Had the author said, “The paternal grandfather, however remote, together with full or paternal half-brothers, is like one of them,” it would have been clearer than his wording, “a child of both parents.” Nevertheless, one advanced in the pursuit of knowledge understands that “a child of both parents” means full brothers. Thus, the grandfather is like one of them. If a deceased person leaves a grandfather and one full brother, the grandfather is like the brother, and each receives one-half. If there are two full brothers, he receives one-third. But if he is like one of them and equal division reduces his share to less than one-third of the estate—as in the case of a grandfather and three full brothers—then, if we say that he is like one of them, he would receive one-quarter. What, then, should we do? The answer is that the author says: