People in the time of Jaahiliyyah (pre-Islamic period of ignorance) used to assign the inheritance of the deceased to the eldest among his sons, excluding his young children, and women relatives like daughters, wives, mothers and sisters; or give it to his brother or paternal uncle, under the pretext that the children and women were too powerless to protect the sanctities that should be protected, take retaliation, gain booty (from wars) and fight the enemies. However, Allah The Almighty invalidated this pre-Islamic custom, and assigned to women and children a share of the inheritance of the deceased, and made their share an obligatory right, no matter how little or much the inheritance might be, as shown in His statement (which means):
{For men is a share of what the parents and close relatives leave, and for women is a share of what the parents and close relatives leave, be it little or much -- an obligatory share.} [Quran 4:7] {Allah instructs you concerning your children: for the male, what is equal to the share of two females. But if there are [only] daughters, two or more, for them is two thirds of one's estate. And if there is only one, for her is half.} [Quran 4:11]He Says about the inheritance of the mother (what means):
{But if he had no children and the parents [alone] inherit from him, then for his mother is one third. And if he had brothers [or sisters], for his mother is a sixth.} [Quran 4:11]
About the share of the wife, He Says (what means):
{And for the wives is one fourth if you leave no child. But if you leave a child, then for them is an eighth of what you leave.} [Quran 4:12]
Allah The Almighty accorded inheritance for women in the following way:
One daughter gets half the inheritance
Two or more daughters get two-thirds the inheritance
The mother gets one-third or one-sixth of the inheritance
The wife gets one-fourth or one-eighth of the inheritance
The half-sister from the side of the mother gets one-sixth
The full sister or the half-sister from the side of the father gets half the inheritance, or half the share of her brother.
It must be borne in mind that all of this is accorded them as their right, when they received nothing in the pre-Islamic days of Jaahiliyyah.
Contrast this with the modern era of Jaahiliyyah, which is no better than the ancient Jaahiliyyah in many of its aspects, which gives room to deprive men, women and children of their rightful inheritance, and instead allows the owner of the inheritance to assign his property, which Allah The Almighty made a means of people's sustenance, to animals.
The system of inheritance set by Islam is distinguished from all modern human laws of inheritance in that Islam adopts a moderate attitude -- between Communist socialism on one extreme, and capitalism and other similar doctrines that call for complete freedom of a person to dispose of his wealth according to his own whims on the other extreme. Communist socialism, as outlined by Karl Marx, rejects the principle of inheritance, and regards it as an erroneous act that opposes the principles of justice. Thus, it gives nothing to the deceased's offspring or next of kin.
Capitalism and its corresponding economic systems, on the contrary, give the owner the full freedom to dispose of his property as he likes. He has the right to deprive all his kith and kin of his inheritance and bequeath it to a stranger, say, a friend or an employee. A man or a woman, in Western societies, even has the right to bequeath the whole or some of his/her property to a dog or a cat!
According to the Islamic system, inheritance is obligatory for both the owner of the property and the heir as well. The owner has no right to prevent any of his heirs from receiving his inheritance; and the heir gets his share, with no need for a court judgment. In some systems, the law affirms inheritance only with a court judgment, since in their sight, it is optional and not compulsory to bequeath and receive inheritance.
The Islamic system limits the right of inheritance within the sphere of the family. It requires a sound relationship through blood or marital relation, and since Walaa’ (allegiance of an ex-slave to his ex-masters) resembles kinship, it was joined with the categories of kinship. In this way, neither an adopted child, nor a child born out of wedlock has the right to inheritance. Within the limits of the family, the closest of kin, under Islam, is given preference, followed by the next of kin to the deceased.
However, in the other systems, the case is quite different. According to the Jews, for example, the heirs are the male sons, and the share of the eldest is equal to the share of two brothers, whether the child is legitimate or illegitimate. Moreover, the eldest son is not deprived of his share even if he is born from an illegitimate marriage.
According to the Western system, a stranger -- like a friend or an employee – is eligible to receive inheritance, and the same applies to the child born out of wedlock.
The Islamic system assigns to the young child a share from the inheritance of his father equal to that of his eldest brother. Thus, there is no differentiation between the fetus in the mother's womb and the eldest son in a big family. The Islamic system also does not differentiate between the eldest son and his brothers, as is the case in the corrupted Jewish canon, and the British law. That is because the young children might be in need of money to build their lives, and to meet their living expenses, more than their older brothers who can work and gather for themselves independent property.
The Islamic system also assigns a share of the inheritance to women. The mother, wife, daughter, son's daughter, sister, and other women relatives, have definite shares in the inheritance of the deceased, to ensure them an honorable life, free from the humiliation of destitution and mortification of poverty, unlike some systems that deprive the women of inheritance under all circumstances. Some laws previously deprived the wife of inheritance, and she was not given any share in it. In the past, the Jews did not give women any portion of the inheritance.
The Islamic system has made 'need' the basic criterion for preference in inheritance. The deceased person’s children need his money more than his father because they are likely to face greater difficulty in fulfilling their requirements, being young and at a stage where they are beginning their life, unlike their grandfather. Moreover, the duties and obligations of the son under the Sharee‘ah (legislation) of Islam are more than those of his sister. He is the one required to provide for himself once he reaches the age of maturity, and he is also required to pay his wife her dowry, provide for her and for the children. He is responsible for the expenses of education, medical treatment, clothing…etc. In addition to this, he is required to provide for his father or relatives if they are poor. However, the girl is more likely to have someone to provide for her, and not the other way round, since she will get married and will be the responsibility of her husband.
These are some of the merits that distinguish the inheritance system in Islam from the old and contemporary laws that were legislated by human beings and that keep changing every now and then.