Esther 9:30-31

30So they sent letters to all the Jews who lived in the 127 regions of Xerxes' kingdom. The message was to help them live safely in peace.

31It told the Jews how to have the days of Purim as a holiday at the right time each year. This was a rule that came from the Jewish man, Mordecai, and from Queen Esther. The message also said that the Jews should remember the sad times, and they should fast.