פירוש על בבא בתרא 108:8

But Samuel said, The law of the land is the law - All taxes, tariffs, and customs of the lawmakers of kings, who regularly lead their kingdom, it is the law, for all the citizens have accepted the king's statutes and laws of their own free will. Therefore, it is a complete law, and one cannot retain ownership over the money that belongs to his fellow according to the decree of the king, for that is theft.