Is it permissible to divide the father's inheritance (a house consisting of 3 floors) after the mother added two more floors with her own money, such that each son gets an apartment, and the daughter gets an apartment by mutual consent, and the fifth apartment (owned by the mother) goes to the male children only, excluding the daughter, after a long life for the mother?

The general rule in inheritance is that a male receives the share of two females. However, adult, competent heirs may waive their share or a part of it. The wife (mother) receives one-eighth of the house. She may donate what she owns of floors or apartments to her children. If the heirs agree that the sister should receive a share equal to that of the males, there is no harm, and the excess over her legal share is considered an act of charity and maintaining kinship ties.

Regarding the fifth apartment: 1. If the mother gifted it to her children during her lifetime and transferred ownership to them, and specifically allocated it to the males with the daughter's consent, there is no harm. 2. However, if she did not gift it during her lifetime but bequeathed it to the males after her death, this is a will to an heir, which is forbidden and invalid in Islamic law. The apartment then becomes part of the inheritance to be divided legally among all heirs after her death. If the daughter then agrees to forgo her share for her brothers, that is permissible; otherwise, she must be given her share.

A forbidden will becomes valid if the heirs approve it, because the prohibition is for their right, and if they agree to waive their right, the will is executed. The children do not have the right to agree on the fate of this apartment now; rather, the matter rests with their mother. She may gift it to her children now with everyone's consent, or she may keep it under her ownership so that it becomes an inheritance for everyone after her death.