Esther 9:20

20. Mordecai wrote these things Namely, the things or occurrences that transpired throughout the Persian empire on the thirteenth, fourteenth, and fifteenth of Adar. He wrote a report of the matter, as of something worthy to be chronicled for everlasting remembrance, and with this record he also sent letters unto all the Jews throughout the empire of Ahasuerus, proposing to them what is stated in the next two verses. Mordecai’s official position in the Persian court enabled him to establish this festival as no other Jew could have done. He could issue orders with royal authority, and use the posts and agents of the empire to facilitate his plans. The statement here made, that Mordecai chronicled these events, and wrote letters to all the Jews, will not warrant the conclusion that he was the author of this Book of Esther, but is sufficient to show that such a conclusion is not therefore improbable.