Esther 9:28-29

9:28 These days were to be remembered and to be celebrated in every generation and in every family, every province, and every city. The Jews were not to fail to observe these days of Purim; the remembrance of them was not to cease among their descendants.

9:29 So Queen Esther, the daughter of Abihail, and Mordecai the Jew wrote with full authority to confirm this second letter about Purim.