What is the ruling on a father selling his apartment to his poor daughter, and (consequently) disinheriting her from her mother's apartment after their death, on the pretext that she had acquired the first apartment?

An father selling his apartment to his poor daughter can be understood in two ways:

The first: The sale is symbolic, not real, and the house is registered in her name so she can take it after his death. This is a bequest to an heir, and it is not valid unless the rest of the heirs agree to it.

The second: The sale is symbolic, and he hands over the house to her during his lifetime while he is in good health, and she pays no price or a very small amount. This is a gift (hibah), and justice among children is required, unless there is a legitimate reason, such as one of them being poor. In that case, there is no harm in the father singling out his poor daughter with the gift.

If the father gifts the apartment to his daughter for a legitimate reason, she should not be prevented from her rightful share of her mother's inheritance after her death, because a gift does not nullify the right to inheritance. Everyone should fear Allah and follow His law concerning gifts, bequests, and the division of inheritance.