Lots, Feast of Purim: The: Mode of Celebrating

This was done on the thirteenth day of the month of Adar, and on the fourteenth day they rested, making it a day of feasting and joy. …

…as the days on which the Jews gained rest from their enemies and the month in which their sorrow turned to joy and their mourning into a holiday. He wrote that these were to be days of feasting and joy, of sending gifts to one another and to the poor.