Ruling on bequeathing to the second wife to the exclusion of the first wife and her children

A message has reached the program from Iraq, Nineveh (M.H.). The sender of the message says: Is it permissible for a man to write a will giving all that he owns to his wife, and leaving his children from the wife who preceded her?
Answer: He does not have the right to do that; because the Messenger (peace be upon him) said: This is if it is a bequest. But if he intends to hasten that for her and give her his wealth while he is in good health, of sound mind, and capable of managing his affairs, if he wishes to give her something from his wealth, there is no harm, even if he does not give his children anything.
But if he has a second wife, he should be just between them. As for if he has only one wife and he wishes to give her half of his wealth, or a third of his wealth, or all of his wealth, and he is of sound mind and guided, there is no harm in that for him, and he is not prevented from disposing of his wealth by giving it to his wife or distributing it among the poor. Abu Bakr (may Allah be pleased with him) spent all of his wealth in the cause of Allah... in supporting the religion of Allah, may Allah be pleased with him and grant him satisfaction. Yes.
But his holding back some of his wealth and not hastening to give it away is better for him, as Ka'b did—when Allah turned to him in mercy—when he wanted to give away all of his wealth in charity, he (peace be upon him) said to him: His holding back some of the wealth; a quarter of the wealth... half of the wealth is better, so that he does not need people.
The presenter: This man, Your Eminence the Shaykh, has a deceased wife who left behind children, then he married a second wife who also has children, and she suggested to him that he write all that he owns in her name, for her and her children, and leave the first deceased wife?
The Shaykh: This requires consideration. If the intention is for her and her children, and he has children from the first wife, it is not permissible.
But if the intention is to give to her only, to give to her only, as for the children, no, then there is no harm in giving her something from his wealth and holding back what Allah has made easy for him. But if the intention is to use a stratagem to give to her children to the exclusion of the children of the first wife, then this is reprehensible, and stratagems are invalid, and the Messenger (peace and blessings be upon him) said: . Yes.