What is the distribution among a full brother and sister, a half-brother (from the father) or more, and the grandfather?
Chapter on Inheritance of the Grandfather
Al-Mughni
Book of Inheritance Shares (Farā'id)
Primary text
The grandfather receives one-third (Al-Thuluth). According to two specific scholars (implied to be different from the main ruling body), the grandfather receives two-fifths (Al-Khumsayn), the full brother two-fifths, and the full sister one-fifth. The division between the grandfather, brother, and sister is partitioned into five shares: two for the grandfather, two for the brother, and one for the sister. Participatory division (Muqasama) is better for the grandfather here, yielding one-fifth of the wealth, which is preferable to one-third.
Supporting text
Whenever the brothers are fewer than two, or their equivalent among females (like three sisters, two sisters, one brother, or one sister), only participatory division (Muqasama) is applied, treating them as equivalent to one brother. This is the position of Zayd, Ali, and Abdullah, provided they are residuaries (asaba). If the surviving relatives are only sisters, Ali and Ibn Mas'ud assign fixed shares (Furoodh) to the sisters first, and the grandfather receives what remains.