Many cultures in large nations like Achashverosh’s would have their own unique set of rules, customs, and even mores. Here, Haman is stressing that Jewish laws not only different, but even antagonistic to the laws of the land. According to the Talmud (Megillah 13b), Haman is complaining that the Jews “won’t eat our food, won’t marry from us, won’t marry to us.” Haman even uses his knowledge of Jewish law to defame Judaism. He tells the king that if a fly were to touch a Jew’s cup, he would remove it and continue drinking. However, if the king were to touch a Jew’s cup, the Jew would throw the wine away. Alluding to the law of yayin nesech (see Talmud, Avodah Zarah 30a), Haman is telling the king that the Jews view the Persians as unclean (see the Targum Sheini).
According to Rav Dovid Feinstein, Haman is saying the Jews view their own laws as superior, and therefore even trumping, the king’s gentile law. On one hand, he is right. Although the Talmud in numerous places (Gittin 10b, Baba Kama 113a, Baba Basra 54b, Nedarim 28a) notes a concept called “dina d’malchusa dina” (“the law of the kingdom is the law”) which means is that Jews are expected to follow the laws of the lands in which we find ourselves, this is only true as long as those laws do not directly contradict Jewish law.
On the other hand, as Megillas Sefer learns, Haman is saying that the Jews even go to the extreme measure of mutilating their sons (through circumcision) to avoid intermarrying with the gentiles around us. Poor, little innocent children are cut for their parents’ religious fanaticism. Interestingly, had it not been a command, its cruelty would make it abhorrent. Rav Hirsch (Collected Writings, Volume II, 385) writes, “In exile, in disrepute, tiny to behold, yet always conspicuous, it is a nation which calls attention to itself, prods others into action and yet, despite its dispersal, manages to preserve its unique heritage and even to transmit it from one generation to the other.”
The Targum Sheini writes that Haman’s criticism of the Jews here was that the Jews “have warm water in winter and cold water in summer.” The Ben Ish Chai explains that Haman is saying the Jews focus on physical pleasure. He also says notes that the Jews manipulate their own calendars from twenty-nine to thirty days, depending on when they want Rosh Chodesh to fall out. In Haman’s estimation, these designations are arbitrary and to the Jews’ own benefit.