What is the ruling regarding the status assigned to the paternal aunt ('Ammah') and maternal aunt ('Khala') for substitution purposes?
Chapter on Distant Kindred (Dhawu al-Arham)
Al-Mughni
Book of Inheritance Shares (Farā'id)
Primary text
The correct ruling is to substitute the paternal aunt for the father and the maternal aunt for the mother. This is supported by three proofs: First, a narration from al-Zuhri that the Prophet, peace be upon him, said: "The paternal aunt is in the position of the father when no father exists between them, and the maternal aunt is in the position of the mother when no mother exists between them." Second, this was the established position of Umar, Ali, and Abdullah, with no dissenting view from the Companions. Third, the father is the strongest link for the paternal aunt, and the mother is the strongest link for the maternal aunt; thus, they are substituted based on these stronger relationships, similar to how the daughter of a brother or cousin is substituted for her parent rather than her sibling.
Supporting text
Some scholars substituted the paternal aunt for the paternal uncle, which is the second narration from Ahmad. Others substituted her for the grandfather, as narrated from al-Thawri and Abu Ubayd. Others substituted the maternal aunt for the grandmother. This dispute arose because the paternal aunt has four kinship links: the father and uncle (as siblings) and the grandfather and grandmother (as parents).