What is the ruling on a grandfather giving a plot of land to his daughter to the exclusion of her other siblings? And what should the daughter do with this land if it is not rightfully hers?

It is permissible for a person to gift their property to their children during their lifetime, but they must be just between them, either by giving the female the same share as the male, or by giving the male the same share as two females.

If the grandfather was just in his first gift, then he is not permitted to favor his daughter with this land, and it is not permissible for the daughter to take it if it becomes clear that her father made a mistake. Rather, it must be returned to the estate and divided according to Islamic law.

However, if the grandfather was not just in his first gift, and he gave the daughter that land to achieve justice, then he has done well, and the children have no right to object. The father must then rectify the lack of justice.