Esther 9:27-32 NIV

27 the Jews took it on themselves to establish the custom that they and their descendants and all who join them should without fail observe these two days every year, in the way prescribed and at the time appointed.
28 These days should be remembered and observed in every generation by every family, and in every province and in every city. And these days of Purim should never fail to be celebrated by the Jews—nor should the memory of these days die out among their descendants.
29 So Queen Esther, daughter of Abihail, along with Mordecai the Jew, wrote with full authority to confirm this second letter concerning Purim.

References for Esther 9:29

30 And Mordecai sent letters to all the Jews in the 127 provinces of Xerxes’ kingdom—words of goodwill and assurance—

References for Esther 9:30

31 to establish these days of Purim at their designated times, as Mordecai the Jew and Queen Esther had decreed for them, and as they had established for themselves and their descendants in regard to their times of fasting and lamentation.

References for Esther 9:31

32 Esther’s decree confirmed these regulations about Purim, and it was written down in the records.