Parashat Zachor teaches: “remember what Amalek did to you on your journey after you left Egypt" (Devarim 25:17-19). The Torah also discusses other nations who threatened Bnai Israel, including the seven peoples of the Land of Israel, the Ammonites and Moabites, and the Egyptians. Yet, there is a special requirement to remember Amalek and not to forget it.
What is so special about Amalek? Some scholars hold that the Amalekites continue as an ethnic group that is always hostile to the Jews. On the other hand, “Sennacherib, king of Assyria, blended all the nations” (Mishnah Yadayim 4:4; cf Rambam, Laws of Kings 5:4), so how can anyone really be identified as an Amalekite? The Talmud also notes that “some of Haman’s descendants studied Torah in Bnei Brak” (Gittin 57b). Since Haman was an Agagite, from Amalek, so were his rabbinic descendants!
Perhaps remembering Amalek ensures that we are awake to wanton hatred aimed at the Jewish people, regardless of the ethnicity of its purveyors (see Rambam, Laws of Kings 5:5).
(יז) זָכ֕וֹר אֵ֛ת אֲשֶׁר־עָשָׂ֥ה לְךָ֖ עֲמָלֵ֑ק בַּדֶּ֖רֶךְ בְּצֵאתְכֶ֥ם מִמִּצְרָֽיִם׃ (יח) אֲשֶׁ֨ר קָֽרְךָ֜ בַּדֶּ֗רֶךְ וַיְזַנֵּ֤ב בְּךָ֙ כָּל־הַנֶּחֱשָׁלִ֣ים אַֽחַרֶ֔יךָ וְאַתָּ֖ה עָיֵ֣ף וְיָגֵ֑עַ וְלֹ֥א יָרֵ֖א אֱלֹקִֽים׃ (יט) וְהָיָ֡ה בְּהָנִ֣יחַ ה' אֱלֹקֶ֣יךָ ׀ לְ֠ךָ מִכָּל־אֹ֨יְבֶ֜יךָ מִסָּבִ֗יב בָּאָ֙רֶץ֙ אֲשֶׁ֣ר יְהוָֽה־אֱ֠לֹקֶיךָ נֹתֵ֨ן לְךָ֤ נַחֲלָה֙ לְרִשְׁתָּ֔הּ תִּמְחֶה֙ אֶת־זֵ֣כֶר עֲמָלֵ֔ק מִתַּ֖חַת הַשָּׁמָ֑יִם לֹ֖א תִּשְׁכָּֽח׃ (פ)
(17) Remember what Amalek did to you on your journey, after you left Egypt— (18) how, undeterred by fear of God, he surprised you on the march, when you were famished and weary, and cut down all the stragglers in your rear. (19) Therefore, when the LORD your God grants you safety from all your enemies around you, in the land that the LORD your God is giving you as a hereditary portion, you shall blot out the memory of Amalek from under heaven. Do not forget!
מִצְוַת עֲשֵׂה לְהַחֲרִים שִׁבְעָה עֲמָמִין שֶׁנֶּאֱמַר (דברים כ יז) "הַחֲרֵם תַּחֲרִימֵם". וְכָל שֶׁבָּא לְיָדוֹ אֶחָד מֵהֶן וְלֹא הֲרָגוֹ עוֹבֵר בְּלֹא תַּעֲשֶׂה שֶׁנֶּאֱמַר (דברים כ טז) "לֹא תְחַיֶּה כָּל נְשָׁמָה". וּכְבָר אָבַד זִכְרָם:
It is a Positive Commandment to exterminate the Seven Nations, as it says, “surely, you shall destroy them” (Deut. 20:17). Anyone who comes across any of these nations and fails to kill them violates a Negative Commandment, as it says, “you shall not keep alive any soul” (Deut. 20:16). Nonetheless, they have already all been destroyed and their memory forgotten.
וְכֵן מִצְוַת עֲשֵׂה לְאַבֵּד זֵכֶר עֲמָלֵק. שֶׁנֶּאֱמַר (דברים כה יט) "תִּמְחֶה אֶת זֵכֶר עֲמָלֵק". וּמִצְוַת עֲשֵׂה לִזְכֹּר תָּמִיד מַעֲשָׂיו הָרָעִים וַאֲרִיבָתוֹ. כְּדֵי לְעוֹרֵר אֵיבָתוֹ. שֶׁנֶּאֱמַר (דברים כה יז) "זָכוֹר אֵת אֲשֶׁר עָשָׂה לְךָ עֲמָלֵק". מִפִּי הַשְּׁמוּעָה לָמְדוּ זָכוֹר בַּפֶּה לֹא תִּשְׁכָּח בַּלֵּב. שֶׁאָסוּר לִשְׁכֹּחַ אֵיבָתוֹ וְשִׂנְאָתוֹ:
It is a Positive Commandment to obliterate Amalek, as it says, “erase the memory of Amalek” (Deut. 28:19). It is a Positive Commandment to perpetually remember their wicked deeds and their ambush in order to arouse our enmity against them, as it says, “remember what Amalek did to you” (Deut. 25:17). By Tradition we have learned that “remember” means by speech, “do not forget” (Deut. 25:19) – in one’s heart; for it is forbidden to forget their enmity and hatred.
בּוֹ בַיּוֹם בָּא יְהוּדָה, גֵּר עַמּוֹנִי, וְעָמַד לִפְנֵיהֶן בְּבֵית הַמִּדְרָשׁ. אָמַר לָהֶם, מָה אֲנִי לָבֹא בַקָּהָל. אָמַר לוֹ רַבָּן גַּמְלִיאֵל, אָסוּר אָתָּה. אָמַר לוֹ רַבִּי יְהוֹשֻׁעַ, מֻתָּר אָתָּה. אָמַר לוֹ רַבָּן גַּמְלִיאֵל, הַכָּתוּב אוֹמֵר (דברים כג), לֹא יָבֹא עַמּוֹנִי וּמוֹאָבִי בִּקְהַל ה' גַּם דּוֹר עֲשִׂירִי וְגוֹ'. אָמַר לוֹ רַבִּי יְהוֹשֻׁעַ, וְכִי עַמּוֹנִים וּמוֹאָבִים בִּמְקוֹמָן הֵן. כְּבָר עָלָה סַנְחֵרִיב מֶלֶךְ אַשּׁוּר וּבִלְבֵּל אֶת כָּל הָאֻמּוֹת, שֶׁנֶּאֱמַר (ישעיה י), וְאָסִיר גְּבוּלֹת עַמִּים וַעֲתוּדוֹתֵיהֶם שׁוֹשֵׂתִי וְאוֹרִיד כַּאבִּיר יוֹשְׁבִים. אָמַר לוֹ רַבָּן גַּמְלִיאֵל, הַכָּתוּב אוֹמֵר (ירמיה מט), וְאַחֲרֵי כֵן אָשִׁיב אֶת שְׁבוּת בְּנֵי עַמּוֹן, וּכְבָר חָזְרוּ. אָמַר לוֹ רַבִּי יְהוֹשֻׁעַ, הַכָּתוּב אוֹמֵר (עמוס ט), וְשַׁבְתִּי אֶת שְׁבוּת עַמִּי יִשְׂרָאֵל וִיהוּדָה, וַעֲדַיִן לֹא שָׁבוּ. הִתִּירוּהוּ לָבֹא בַקָּהָל:
On that very day, Yehuda, an Ammonite convert, came and stood before them in the Beit Midrash, and said to them, "What is my status with regard to whether I can enter [via marriage] into the congregation [of Israel]?" Rabban Gamliel said to him, "You are prohibited." Rabbi Yehoshua said to him, "You are permitted." Rabban Gamliel said to him, "The verse says, (Deuteronomy 23:4) 'An Ammonite and a Moavite may not enter into the congregation of the Lord, even to the tenth generation,' and so forth." Rabbi Yehoshua said to him, "And are the Ammonites or Moavites still [dwelling] in their own place? Sancheriv, king of Assyria, already arose and blended all the nations, as the verse says, (Isaiah 10:13) 'I have removed the borders of nations, and I have plundered their treasures, and like a great warrior laid low the inhabitants.'" Rabban Gamliel said to him, "The verse [also] states, (Jeremiah 49:6) 'And afterwards I shall return the captives of the children of Ammon,' and they are already returned." Rabbi Yehoshua said to him, "The verse [also] states, (Amos 9:14) 'And I shall return the captives of my nation Israel,' [and Judah], and they are not yet returned." They [the Sages, subsequently] permitted him [the Ammonite convert] to enter into the congregation.
The Gemara adds that some of Haman’s descendants studied Torah in Bnei Brak, and some of Sisera’s descendants taught children Torah in Jerusalem, and some of Sennacherib’s descendants taught Torah in public. Who are they? They are Shemaya and Avtalyon, the teachers of Hillel the Elder.