Is it permissible for children to write a new waiver for a kirat of their father's land and match his signature without his knowledge, after the first waiver, in which the father had waived this kirat to them, was lost, for fear of his refusal to waive it again, knowing that the kirat is the father's inheritance from the children's mother?

It is not permissible to revoke a gift after its acceptance, except for the father, who may revoke what he has given to his child. This is based on the Prophet Muhammad's (peace be upon him) saying: "It is not lawful for a man to give a gift and then revoke it, except for a father in what he gives to his child." It is not permissible for children to deceive their father to waive his right to revoke the gift. Rather, they are obligated to honor him and treat him kindly.