Bequesting entire estate to one heir
13-3-2017 | IslamWeb
Question:
I was born and raised in a Western society. I am married, and we have one son who is living with us with his family. My husband has one boy and one girl from a previous marriage. My husband and I bought a house together many years ago. I am receiving a government pension that I put in a join account on my name, my husband's name, and our son's name. This is the practice here to protect and be able to access the account in case of my death. I want to give our son all what I have in money and property as a gift while I am alive with the condition that he can have the gift only after my death. I do not have any other person who can inherit me except for our son and my husband. My husband agrees with my will to give our son all that I own. My question is: Is is permissible for me to do it this way according to Islam? May Allaah reward you.
Answer:
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, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
What you wish to do is a bequest (Wasiyyah), and not a gift (Hibah), as you said that he can only have it after your death. A bequest made in favor of an heir cannot be executed except with the consent of all the heirs. The Prophet, sallallaahu ‘alayhi wa sallam, said, "Allah has given each person his due share of the inheritance, so no bequest is to be made in favor of an heir." [At-Tirmithi] The version cited by Ad-Daaraqutni reads, "...unless approved by the heirs." Al-Haafith Ibn Hajar 
classified the chain of narration of this hadeeth as good in his book 'Buloogh Al-Maraam'.
The consent of the rest of the heirs is effective only after the death of the testator, when they become entitled to the estate. The present consent of the father is of no value, even if he and the son are your only heirs.
In any case, there is no religious impediment to making such a bequest; however, it cannot be executed except with the consent of all the heirs after your death.
We advise you, though, to not forget your own share of this good if you have failed to offer charity during your lifetime. Allah blessed us with the right to allocate a share of the estate (as a bequest) to be offered in charity on the condition that it does not exceed one third of the estate, and the rewards for this charity shall reach you after your death. The Prophet, sallallaahu ‘alayhi wa sallam, said, "Allah has bestowed upon you a charity by the disposal of one third of your wealth at the time of your death so that you may be able to add to the record of your good deeds." [Ahmad, Ibn Maajah, and others]
Allah knows best.