Chapter on ḥajb (exclusion)
This chapter holds a special place among the rulings of inheritance, because mastering its details guarantees that rights reach those to whom they are due. Ignorance of its rulings, by contrast, brings grave peril: the estate may be handed to someone who is not legally entitled while the rightful heir is deprived. For that reason some scholars have declared, “It is forbidden for anyone who does not know the rules of ḥajb to issue legal opinions on inheritance.”

Linguistically, ḥajb means “to prevent.” One says ḥajabahu when he prevents someone from entering, and a ḥājib is, by definition, the doorkeeper who bars people from the ruler’s presence.

In the technical usage of the jurists of inheritance, ḥajb refers to excluding a person who possesses a cause of inheritance—either completely, or by reducing him from the larger of his two potential shares.

In the law of succession, ḥajb is divided into two categories.

The first category: exclusion due to personal attributes.
This applies to anyone who possesses one of the three disqualifying attributes: slavery, homicide, or religious difference. Whoever is marked by any of these characteristics inherits nothing; his existence is treated as though he were not present at all.