Esther 9:28-32

So these days were to be remembered and celebrated throughout every generation, every family, every province and every city; and these days of Purim were not to cease from among the Jews, nor their memory fade from their descendants. Then Queen Esther, the daughter of Abihail, with Mordecai the Jew, wrote with full power and authority to confirm this second letter about Purim. He sent letters to all the Jews, to the 127 provinces of the kingdom of Ahasuerus, in words of peace and truth, to establish these days of Purim [to be observed] at their appointed times, just as Mordecai the Jew and Queen Esther had established for them, and as they had established for themselves and for their descendants with instructions regarding their times of fasting and their lamentations (expressions of needing help). The command of Esther established these customs for Purim, and it was written in the book [of the royal archives].