Is it a condition for organ transplantation from a deceased person to have the deceased's permission before their death, or the heirs' permission after their death, or both?

Therefore, the deceased's permission through a will before his death, or the permission of his heirs after his death, is sufficient. It is permissible to transfer an organ from a deceased person to a living person if the life of the living person or the سلامة [soundness/proper functioning] of an essential organ in him depends on it, provided the aforementioned permission is given, or with the approval of the ولي المسلمين [guardian of the Muslims/ruler] if the deceased is of unknown identity or has no heirs.