The decree of Esther confirmed these matters - It was received by the Jews universally with all respect, and they bound themselves to abide by it.
The Vulgate gives a strange turn to this verse: Et omnia quae libri hujus, qui vocatur Esther, historia continentur; "And all things which are contained in the history of this book, which is called Esther."
The Targum says, And by the word of Esther all these things relative to Purim were confirmed; and the roll was transcribed in this book. The Syriac is the same as the Hebrew, and the Septuagint in this place not very different.
As “the book” elsewhere in Esther always means a particular book - “the book of the chronicles of the kings of Media and Persia” - Esther 2:23; Esther 6:1; Esther 10:2 it seems best to give it the same sense here.