To not forget what he did to us: That we have been prevented from forgetting that which Amalek did with us — meaning to say, his starting to harm us [before anyone else]. And about this is it stated (Deuteronomy 25:19), “do not forget.” And it is written in Sifrei [that] “Remember” is with the mouth [and] “do not forget” is with the heart — meaning to say do not cast down hatred of him and do not remove it from you soul, in the manner that you will forget it.
From the roots of this commandment and all of its content is written in its positive commandment in this Order (Sefer HaChinukh 603) — and take it from there and quench your thirst.
שֶׁלֹּא לִשְׁכֹּחַ מָה שֶׁעָשָׂה לָנוּ – שֶׁנִּמְנַעְנוּ מִלִּשְׁכֹּחַ מָה שֶׁעָשָׂה עִמָּנוּ עֲמָלֵק, כְּלוֹמַר, הַתְחָלָתוֹ לְהַזִּיק לָנוּ, וְעַל זֶה נֶאֱמַר בְּפָרָשָׁה זוֹ שֶׁל עֲמָלֵק (דברים כה יט) לֹא תִּשְׁכָּח. וְכָתוּב בְּסִפְרֵי זָכוֹר בַּפֶּה, לֹא תִּשְׁכָּח בַּלֵּב, כְּלוֹמַר לֹא תַּשְׁלִיךְ שִׂנְאָתוֹ וְלֹא תְּסִירָהּ מִנַּפְשְׁךָ בְּעִנְיָן שֶׁתִּשְׁכַּח אוֹתָהּ.
To not forget what he did to us: That we have been prevented from forgetting that which Amalek did with us — meaning to say, his starting to harm us [before anyone else]. And about this is it stated (Deuteronomy 25:19), “do not forget.” And it is written in Sifrei [that] “Remember” is with the mouth [and] “do not forget” is with the heart — meaning to say do not cast down hatred of him and do not remove it from you soul, in the manner that you will forget it.
מִשָּׁרְשֵׁי הַמִּצְוָה וְכָל עִנְיָנָהּ כָּתוּב בְּמִצְוַת עֲשֵׂה שֶׁלּוֹ שֶׁבְּסֵדֶר זֶה (מצוה תרג), וְקָחֶנּוּ מִשָּׁם וְתַרְוֶה צִמְאוֹנְךָ.
From the roots of this commandment and all of its content is written in its positive commandment in this Order (Sefer HaChinukh 603) — and take it from there and quench your thirst.