How can a father's will be executed regarding giving 10% of the inheritance as charity, while adhering to his will not to sell any real estate, and for the heirs to buy each other's shares if one wishes to exit? Is his will not to sell the real estate binding, and is the will to give 10% of the future income from rented properties binding?

It is permissible for a person to bequeath a third of his wealth or less, and the heirs are obligated to execute his will, as Allah Almighty says: (from after any will which he may have bequeathed or a debt). However, a will stipulating that real estate not be sold is invalid. Upon the death of the testator, the wealth transfers to the heirs, and they may dispose of it as they wish, for what the deceased leaves becomes the property of his heir.