Is it permissible to retract the waiver of an inheritance that occurred during the lifetime of the deceased and at his request, after his death?

The waiver mentioned before the death of the inheritee is not considered valid, and the heir has the right to take his share that he waived. He may waive it after the death of his inheritee if he is an adult and of sound mind. This waiver is considered a gift, and its validity is subject to the conditions required for a gift.