Is it permissible for a father to register land in the names of the daughters and wife of one of his sons with the intention of harming an inheriting son? And is what has been registered deducted from the son's inheritance?

A bequest to a non-heir is permissible within the limit of one-third of the estate, provided that there is no intention to harm the heirs. Granddaughters and the testator's wife are not heirs, so a bequest to them is permissible. However, if the intention of the bequest is to harm the heir son or to increase the share of another son, then it is forbidden, based on the Almighty's saying: "after any bequest which was made or debt, without causing harm" (An-Nisa/12). This is also supported by what Ibn Abbas, may Allah be pleased with him, said: "Causing harm through a bequest is one of the major sins." This prohibition includes bequests, gifts, and simulated sales if the intention is to harm the heirs. The one who does this should be advised and warned.