What is the ruling on a father demanding ownership of parts of a building constructed on his land after he permitted his children to build and pledged that what they built would be theirs, then changed his mind, demanding more than half of the building, claiming partnership in it and that he had willed it so, despite his affluence and lack of need, and his desire to bequeath these parts to his other affluent children?

A father must be just among his children in giving gifts, and he should give the male the equivalent of the share of two females. What a son builds with his father's permission belongs to the son, and the father is not allowed to take from his son's money unless he is in need, and provided that it does not harm the son or give his money to another child. If the father dies, then the one who built on his land with his permission is only entitled to the value of the construction, and then he shares with the heirs in the land and the building that his father built. A father has the right to revoke a gift given to his child, and he must pay the son the value of the construction.