Esther 9:29-31

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.)