What is the ruling of Islamic law regarding a father selling a portion of his land and house to his second wife without receiving payment, with the intention of disinheriting his children from his deceased wife, and do these children have the right to claim their share in these properties?

If a husband sells his house to his wife without a price, it is a gift (hiba). This gift becomes valid and the wife takes possession of it upon actual physical possession (qabd) during the husband's lifetime and good health. However, if it occurs during a life-threatening illness (marad al-mawt al-makhuf), it is considered a bequest (wasiyya) to an heir, and it is not valid unless the other heirs consent. A chronic life-threatening illness is one that incapacitates the person and confines them to bed. If the gifted house is the donor's residence, the validity of the gift is a matter of dispute among scholars. Assuming its validity, it is not completed unless the husband vacates it of his belongings. In all cases, the matter is referred to the judiciary to determine the validity and enforceability of the gift.