Esther 9:20-23

Mordecai wrote down everything that had happened. Then he sent letters to all the Jewish people in all the empire of King Xerxes, far and near. He told them to celebrate every year on the fourteenth and fifteenth days of the month of Adar, because that was when the Jewish people got rid of their enemies. They were also to celebrate it as the month their sadness was turned to joy and their crying for the dead was turned into celebration. He told them to celebrate those days as days of joyful feasting and as a time for giving food to each other and presents to the poor. So the Jewish people agreed to do what Mordecai had written to them, and they agreed to hold the celebration every year.