Midrash su Ester 8:17

“It was during the days of Aḥashverosh…” Rabbi Levi and the Rabbis, Rabbi Levi said: Aḥashverosh is Artaḥshasta. The Rabbis say: [He was called] Aḥashverosh, since anyone who remembers him, his head hurts [ḥoshesh et rosho]. Why did Scripture call him Artaḥshasta? It is because he would anger [martiaḥ] and exhaust [vetash] [others]. Aḥashverosh – Rabbi Yitzḥak and the Rabbis, Rabbi Yitzḥak said: “Aḥashverosh” – as all the troubles came during his days, as it is stated: “there was great mourning among the Jews” (Esther 4:3). “That is Aḥashverosh” – as all the good came during his days, as it is stated: “Joy and gladness for the Jews, a banquet and a holiday” (Esther 8:17). The Rabbis say: “Aḥashverosh” – before Esther came before him; “that is Aḥashverosh” – after Esther came before him, he would no longer copulate with menstruants.

“The king’s decree about what he will do will be heard throughout his entire kingdom, vast as it is, and all wives will give honor to their husbands, from great to small” (Esther 1:20).
Rabbi Levi and Rabbi Yitzḥak, Rabbi Levi said: We are destined to hear a great decree from that one who will become queen. What is that? “There was great mourning among the Jews” (Esther 4:3). Rabbi Yitzḥak said: We are destined to hear a great decree from that one who will become queen. What is that? “There was joy and gladness for the Jews” (Esther 8:17). Rabbi Yehuda son of Rabbi Simon said: The decree of the King of kings will be heard, who said in His wisdom and His understanding: “I will expunge the memory of Amalek” (Exodus 17:14).
“Vast as it is” – Rav and Shmuel, one said: This kingdom is too vast for this sin; and one said: This sin is too great for this kingdom.¹⁷Rav and Shmuel disagree as to whether the word ‘vast’ in the verse refers to the kingdom, or to Vashti’s sin. “And all the wives will give honor to their husbands…”

“There was a Judean man in the Shushan citadel, and his name was Mordekhai, son of Ya'ir, son of Shimi, son of Kish, a Benjamite” (Esther 2:5).
“There was a Judean man [ish] in the Shushan citadel” – ish teaches that Mordekhai, in his generation, was the equivalent of Moses, in his generation, as it is written about him: “And the man [veha’ish] Moses was very humble” (Numbers 12:3). Just as Moses stood in the breach, as it is written: “He said He would destroy them, were it not for Moses His chosen one, who stood before Him in the breach…” (Psalms 106:23); also Mordekhai did likewise: “A seeker of good for his people and spokesman of peace for all his descendants” (Esther 10:3).
Just as Moses taught Torah to Israel, as it is written: “See, I have taught you statutes and ordinances” (Deuteronomy 4:5), also Mordekhai did so, as it is written: “Matters of peace and truth” (Esther 9:30), and as it is written: “Acquire truth and do not sell” (Proverbs 23:23).
“And his name was Mordekhai” (Esther 2:5) – the wicked precede their names: “Naval was his name” (I Samuel 25:25); “Sheva ben Bikhri was his name” (II Samuel 20:21). However, the righteous, their names precede them: “And his name was Manoaḥ” (Judges 13:2); “And his name was Kish” (I Samuel 9:1); “And his name was Elkana” (I Samuel 1:1); “And his name was Boaz” (Ruth 2:1); “And his name was Mordekhai.” It is because they are similar to their Creator, as it is written: “But by My name, the Lord, I was not known by them” (Exodus 6:3).
“Judean” – why was he called Judean? Was he not a Benjaminite?⁶Mordekhai is identified as coming from the tribe of Benjamin in Esther 2:5. It is because he unified the name of the Holy One blessed be He⁷Actions which assert that there is only one God are referred to as “unifying the name.” before all creatures; that is what is written: “[And Mordekhai] would not bow and would not prostrate himself” (Esther 3:2). Was he contrary and violating the king’s decree? Rather, when Aḥashverosh commanded [everyone] to prostrate themselves to Haman, he [Haman] carved an idol [and set it] over his heart, intending that they prostrate themselves to the idol.
When Haman saw that Mordekhai would not prostrate himself to him, he was filled with fury. Mordekhai said to him: ‘There is a Master who exalts over all the exalted; how can I forsake him and prostrate myself to an idol?’ Because he unified the name of the Holy One blessed be He, he is called Judean [Yehudi], meaning by himself [yeḥidi].⁸Just as God is only one [yeḥidi] so was Mordekhai called yeḥidi.
Some say that he was the equivalent of Abraham in his generation. Just as Abraham allowed himself to be put into the fiery furnace and went about causing people to acknowledge the greatness of the Holy One blessed be He – that is what is written: “And the souls they had gotten in Ḥaran” (Genesis 12:5), so too, Mordekhai, in his time, people acknowledged the greatness of the Holy One blessed be He. That is what is written: “Many of the peoples of the land became Jews, as the fear of the Jews had fallen upon them” (Esther 8:17). He unified the name of the Holy One blessed be He, and sanctified it. Therefore, he is called yehudi, as it is written: “A Judean [yehudi] man” – don’t read it as yehudi, but rather, as yeḥidi.