Those who reduce the mother’s share are two in number, as indicated by the Almighty’s words, “But if he has siblings” (al-Nisāʾ 4:11). The majority hold that both a brother and a sister fall under the term “siblings” in this verse without dispute.

Some later scholars, however, said: “I do not move the mother from one-third to one-sixth because of sisters on their own,” claiming that the word “siblings” applies to them only when a brother is present, on the grounds that the masculine overrides the feminine in Arabic usage; the word “siblings” is the plural of “brother,” and “brother” is masculine.

Within the same discussion they disagreed over who receives the one-sixth from which the mother is barred by the presence of siblings when the deceased leaves both parents and siblings. The majority say that this sixth goes to the father in addition to the other four sixths. A report from Ibn ʿAbbās states that the blocked sixth belongs to the siblings who caused the bar, while the father takes two-thirds, for among the ascendants none both bars and then takes the barred portion except the siblings together with the parents. Some scholars regarded the chain linking this report to Ibn ʿAbbās as weak, yet his opinion conforms to legal analogy.

They also differed over the two cases known as al-Gharrāwiyān—when the deceased leaves either (a) a wife and both parents, or (b) a husband and both parents.

According to the majority:
• In the first case, the wife receives one-quarter; the mother receives one-third of what remains, which equals one-quarter of the estate; and the father takes the rest, namely one-half.
• In the second case, the husband receives one-half; the mother receives one-third of what remains, which is one-sixth of the estate; and the father takes the remainder, two-sixths. This is the view of Zayd and the well-known position related from ʿAlī—may Allah be pleased with him.

Ibn ʿAbbās said about the first case: the wife is entitled to one-quarter of the estate, the mother to one-third of it as well, for she is a fixed-share heir, and the father receives what remains as a residuary. He gave the same ruling for the second case: the husband gets one-half, the mother one-third as a named sharer, and the father the remainder. This view was also held by Shurayḥ the judge, Dāwūd, Ibn Sīrīn, and a number of others.

The majority’s main argument is that when the parents inherit alone the mother takes one-third and the father the balance; therefore the same proportion should apply to whatever remains of the estate, lest the mother’s share exceed the father’s, which would contravene basic principles.

The other side’s chief argument is that the mother has a specified fixed share whereas the father is a residuary, and a residuary has no set fraction alongside fixed-share heirs—his portion may decrease or increase.

On the basis of explicit reasoning, the majority’s position appears stronger; without such reasoning, the second view is the clearer. By “reasoning” here I mean the principle that the nearer of a person’s two lines of descent—the father rather than the mother—deserves priority.

Inheritance of Maternal Siblings

The scholars unanimously agree that when only one uterine sibling survives, whether male or female, he or she receives one-sixth. If there are two or more, they share equally in one-third, the male taking exactly the same as the female.