Mordecai recorded these events and sent letters to the Jews near and far, throughout all the provinces of King Xerxes,
calling on them to celebrate an annual festival on these two days.
References for Esther 9:21
He told them to celebrate these days with feasting and gladness and by giving gifts of food to each other and presents to the poor. This would commemorate a time when the Jews gained relief from their enemies, when their sorrow was turned into gladness and their mourning into joy.
So the Jews accepted Mordecai’s proposal and adopted this annual custom.
Haman son of Hammedatha the Agagite, the enemy of the Jews, had plotted to crush and destroy them on the date determined by casting lots (the lots were called ).
But when Esther came before the king, he issued a decree causing Haman’s evil plot to backfire, and Haman and his sons were impaled on a sharpened pole.
That is why this celebration is called Purim, because it is the ancient word for casting lots. So because of Mordecai’s letter and because of what they had experienced,
the Jews throughout the realm agreed to inaugurate this tradition and to pass it on to their descendants and to all who became Jews. They declared they would never fail to celebrate these two prescribed days at the appointed time each year.
These days would be remembered and kept from generation to generation and celebrated by every family throughout the provinces and cities of the empire. This Festival of Purim would never cease to be celebrated among the Jews, nor would the memory of what happened ever die out among their descendants.
Then Queen Esther, the daughter of Abihail, along with Mordecai the Jew, wrote another letter putting the queen’s full authority behind Mordecai’s letter to establish the Festival of Purim.
Letters wishing peace and security were sent to the Jews throughout the 127 provinces of the empire of Xerxes.
These letters established the Festival of Purim—an annual celebration of these days at the appointed time, decreed by both Mordecai the Jew and Queen Esther. (The people decided to observe this festival, just as they had decided for themselves and their descendants to establish the times of fasting and mourning.)
So the command of Esther confirmed the practices of Purim, and it was all written down in the records.