Is making will an obligation? Is it permissible to be done for an heir?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Making a will is merely desirable not an obligation except for the one who should pay Allah's Rights such as Zakaah, Hajj, or people's rights such as debts, deposits, or any property he had taken unlawfully. In this case, it is obligatory upon him to make a will to fulfill the rights of Allah and those of the people.

However, if one calls witnesses to testify for the above rights, then he is no longer obliged to leave a will.

Know that making a will for an heir who has a legal share of the inheritance is not valid. The Prophet said: “Verily, Allah has given every rightful person his right, so there is no bequest for an heir.” [At-Tirmithi and Abu Daawood]

For more benefit that there is no will for an heir, please refer to Fataawa 289471, 302158, 312970, 317632, 336970, and 350614.

Allah knows best.