What is the ruling of Islamic law and secular law on a property gift made by a man to his second wife one month before his death, while he was ill, and do the heirs have the right to annul this gift and return ownership to the deceased?

If a man gives a gift to his wife while he is healthy, or during an illness that is not life-threatening, and the wife has taken full possession of the gift, then the gift is valid, and his children do not have the right to revoke it. However, if the gift was given during a death illness, or if it was not taken possession of before the death of the donor or before he entered into a death illness, then the gift is invalid and is divided with the inheritance among the heirs. For the gift to be valid, possession is required, as Malik narrated from Abu Bakr and Aisha, may Allah be pleased with them. And if the man intends by the gift to favor his children from this wife, then the gift is rejected.