Let’s start with the Qur’an:
It has been ordained upon you, when death is near to one of you, leaving wealth behind, to make a will in favor of parents and close relatives, impartially. This is incumbent upon the pious.—Qur’an 2:180
The other Qur’anic verse that mentions a bequest is:
Those among you who die leaving wives behind are to leave a bequest to the their wives: maintenance for a year and no eviction. —Qur’an 2:240
The first verse is known as the “bequest verse.” The Arabic word “al-waṣiyya” in this verse has been translated to “bequeath,” “make a will,” or “make a bequest.”
Surat ʾal-Nisaʾ was revealed after the revelation of these bequest verses. For this reason, most Muslim scholars concluded that the new revelation of the inheritance rules contained in Surat ʾal-Nisaʾ qualified, and some said abrogated, the previously revealed bequest verses. Basically, Surat ʾal-Nisaʾ changed the discretionary inheritance system to a mandatory default Islamic Inheritance fixed share system.
Because we live in the United States and the default Islamic inheritance system is not the law of the land, the Qur’anic verse directing us to make a will to relatives would be a requirement if we wish the rules of inheritance in Surat ʾal-Nisaʾ to govern the distribution of your estate.
Back to the Islamic law governing bequests: Surat ʾal-Nisaʾ did not prohibit bequests. “[A]fter deducting any bequests you may bequeath, or any debts,” means that a Muslim still had the right to leave a bequest.
But is there a limit to a bequest? Can you leave a bequest to anyone?
The scholars set out to provide answers to these questions from the Qur’an and the Sunna.
It is reported that the Prophet (PBUH) suggested to Saʿd Ibn Abī Waqqās to leave one third as a bequest to a relative: “A third. And a third is much. It is better that you leave your heirs rich than that you should leave them destitute, begging from their neighbors.” Another similar hadith reports that the prophet told Saʿd Ibn Mālik, another companion: “Then bequeath a third. A third is much.”
The next issues that the scholars needed to resolve were whether there is any restriction to whom would be entitled to receive such a bequest. The answer was found in the Sunna. The Prophet Muhammed (PBUH) is reported to have told his followers: ʾAllah has given each person who has a right his due, and there shall be no bequest to an heir [that is inheriting].’
Finally, the scholars sorted out whether leaving a bequest is obligatory, recommended, disliked, or prohibited. It depends on the circumstances.
The obligatory bequest is one you must make. An example of this is when you owe someone a debt, but no one knows about this debt except you and the creditor. In this case, you must include the debt in your will. Another example is if you are wealthy and have poor relatives that are not eligible legal heirs; you are obligated to leave them something.
The recommended bequest is one you should strongly consider. For example, if your legal heirs and relatives are wealthy and not in need, leaving part of your estate for charity is recommended.
The disliked bequest is not recommended. For example, when your estate is not large and your legal heirs and relatives are poor, if you leave part of your small estate to others, the scholars concluded such a bequest is disliked because it will create hardship on your family.
The prohibited bequest is not allowed when following Islamic law. Prohibited bequests include when you leave more than one-third of your estate to non-legal heirs or give a legal heir more than his or her share as stated in the Qur’an. This is based on the famous Hadith of the Prophet: “ʾAllah has given each person who has a right his due, and there shall be no bequest to an heir [that is inheriting].”
To summarize, if you want your estate to be distributed according to Islamic law, you need to have an Islamic will. And you are free to leave bequests up to one third of your estate to a relative, friend, or charity.