Esther 9:23

9:23 So the Jews committed themselves to continue what they had begun to do and to what Mordecai had written to them.

Esther 9:27

9:27 Therefore, because of the account found in this letter and what they had faced in this regard and what had happened to them, the Jews established as binding on themselves, their descendants, and all who joined their company that they should observe these two days without fail, just as written and at the appropriate time on an annual basis.