Esther 8:7-8

7King Xerxes replied to Queen Esther and to Mordecai, ‘You are right! I have already punished Haman with death because he wanted to destroy the Jews. I have also given all of his things to Esther.

8Now you must use my authority to write another law. Write a law that you think will save your people. Then mark the letters with my special ring. Any letter that has my name and the mark of my ring on it has the king's authority. Nobody can ever change it.’