Esth 9:26

“therefore, because of all the words of this letter these days were established, and therefore it was written for future generations to know. and what they saw those who did these deeds, that they did them. and what happened to them What did Ahasuerus see that he used the sacred vessels, and what happened to them? That Satan came and danced among them and slew Vashti. And what did Haman see that he became envious of Mordecai, and what happened to him? They hanged him and his sons. And what did Mordecai see that he did not kneel or prostrate himself, and what did Esther see that she invited Haman?”

“And that these days should be remembered, and kept throughout every generation, every family, every province, and every city,.... And accordingly these days are commemorated by them now, and by all their families, and all in their families capable of it; and these words, "every province", and "every city", are used, as Aben Ezra observes, lest a man should think he was not bound to keep this feast where there were no Jews; for, let him be where he may, he is obliged to keep it: and that these days of Purim should not fail among the Jews; or the observance of them be neglected and cease: nor the memorial of them perish from their seed; neither the memorial of them, nor of the reason of keeping them; wherefore on those days they read the whole book of Esther, fairly written on a roll of parchment, and are careful that none omit the reading of it; rather, they say (w), the reading and learning the law should be omitted, and all commands and service, than the reading this volume, that so all might be acquainted with this wonderful deliverance, and keep it in mind. (w) Lebush & Schulchan, ib. (par. 1.) c. 687. sect. 2.”

“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.”

“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]. Next: Esther Chapter 10”

“Wherefore they called these days Purim after the name Pur. This first על־כּן refers to what precedes and states the reason, resulting from what has just been mentioned, why this festival received the name of Purim. With the second על־כּן begins a new sentence which reaches to Est 9:28, and explains how it happened that these feast-days became a general observance with all Jews; namely, that because of all the words of this letter (of Mordochai, Est 9:20), and of what they had seen concerning the matter (על־כּכה, concerning so and so), and what had come upon them (therefore for two reasons: (1) because of the written injunction of Mordochai; and (2) because they had themselves experienced this event), the Jews established, and took upon themselves, their descendants, and all who should join themselves unto them (proselytes), so that it should not fail (i.e., inviolably), to keep (to celebrate) these two days according to the writing concerning them and the time appointed thereby year by year.”