Mishneh Torah — Negative Mitzvot מצוות לא תעשה, Chapter 59
The full Hebrew text of Mishneh Torah, Negative Mitzvot, Chapter 59, with English translation by Maimonides (Rambam).
שלא יסור מליבנו מעשה עמלק הרע שעשה לנו, שנאמר "לא, תשכח" (דברים כה,יט).
Not to forget the wicked deeds which Amalek perpetrated against us, as [Deuteronomy 25:19] states: "Do not forget."