Esther 9:26

26. they called these days Purim after the name of Pur--"Pur," in the Persian language, signifies "lot"; and the feast of Purim, or lots, has a reference to the time having been pitched upon by Haman through the decision of the lot. In consequence of the signal national deliverance which divine providence gave them from the infamous machinations of Haman, Mordecai ordered the Jews to commemorate that event by an anniversary festival, which was to last for two days, in accordance with the two days' war of defense they had to maintain. There was a slight difference in the time of this festival; for the Jews in the provinces, having defended themselves against their enemies on the thirteenth, devoted the fourteenth to festivity; whereas their brethren in Shushan, having extended that work over two days, did not observe their thanksgiving feast till the fifteenth. But this was remedied by authority, which fixed the fourteenth and fifteenth of Adar. It became a season of sunny memories to the universal body of the Jews; and, by the letters of Mordecai, dispersed through all parts of the Persian empire, it was established as an annual feast, the celebration of which is kept up still. On both days of the feast, the modern Jews read over the Megillah or Book of Esther in their synagogues. The copy read must not be printed, but written on vellum in the form of a roll; and the names of the ten sons of Haman are written on it a peculiar manner, being ranged, they say, like so many bodies on a gibbet. The reader must pronounce all these names in one breath. Whenever Haman's name is pronounced, they make a terrible noise in the synagogue. Some drum with their feet on the floor, and the boys have mallets with which they knock and make a noise. They prepare themselves for their carnival by a previous fast, which should continue three days, in imitation of Esther's; but they have mostly reduced it to one day [Jennings, Jewish Antiquities].

Robert Jamieson, A. R. Fausset & David Brown, 1871 · public domain

Verse 26 They called these days Purim - That is from pari, the lot; because, as we have seen, Haman cast lots to find what month, and what day of the month, would be the most favorable for the accomplishment of his bloody designs against the Jews. See on Est 3:7 (note). And of that which they had seen - The first letter to which this second refers, must be that sent by Mordecai himself. See Est 9:20.

Adam Clarke, 1831 · public domain