The importance of the will is clear for every Muslim. The Prophet SAW said "It is the duty of a Muslim who has anything to bequest not to let two nights pass without writing a will about it." (Sahih al-Bukhari). Also He said "A man may do good deeds for seventy years but if he acts unjustly when he leaves his last testament, the wickedness of his deed will be sealed upon him, and he will enter the Fire. If, (on the other hand), a man acts wickedly for seventy years but is just in his last will and testament, the goodness of his deed will be sealed upon him, and he will enter the Garden." (Ahmad and Ibn Majah)
The will gives the testator an opportunity to help anyone who is not entitled to inherit from him. The will can be used to clarify the nature of joint accounts, those living in commensality, appointment of guardian for one's children and so on. In countries where the intestate succession law is different from Islamic law it becomes absolutely necessary to write a will.
The Islamic will includes bequests and legacies, instructions and admonishments, and assignments of rights. No specific wording is necessary for making a will. In Islamic law the will (wasiyya) can be oral or written, and the intention of the testator must be clear that the wasiyya is to be executed after his death. Any expression which signifies the intention of the testator is sufficient for the purpose of constituting a bequest. However, the will it cannot exceed the one-third.
that debts to Allah (SWT) such as zakah, obligatory expiation etc. should be paid whether mentioned in the will or not. However, there is difference of opinion on this matter amongst the Muslim jurists.
Obstacles to Succession
There are certain impediments to succession: Those are:
(1) Slavery, because a slave has no right to property.
(2) Homicide, a person killing another does not inherit from the latter.
(3) Difference of religion.
(4) Difference of territorial jurisdiction either natural or constructive.