“Mordecai recorded these things. He sent letters to all the Jews who were in all the provinces of King Artaxerxes, both near and far. He enjoined them that they should keep the fourteenth day of the month of Adar and also the fifteenth day of the same month, year by year. These are the days on which the Jews gained relief from their enemies. This is the month that had been turned for them from sorrow into gladness, and from mourning into a holiday. They should make them days of feasting and gladness, days for sending gifts of food to one another, and presents to the poor. Thus the Jews adopted as a custom what they had begun to do, as Mordecai had written to them.”
Mordecai put in a decree for the Jews of the Persian kingdom, a custom that they had already started. This became known as Purim. Each year they should remember what happened to them on the 14th and 15th of Adar. They should exchange food gifts and give to the poor. They were to remember that on this day that they turned from sorrow to gladness and from mourning to feasting. In modern day Judaism, this has become a big holiday eating and drinking for Conservative and Orthodox Jews, much like a Halloween feast. Children dress up and exchange treats. They read the Book of Esther, while booing Haman and cheering Mordecai.