Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 189
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 189, with English translation by Maimonides (Rambam).
לזכור מה שעשה לנו עמלק תדיר, שנאמר: "זכור, את אשר עשה לך עמלק" (דברים כה,יז).
To constantly remember what Amalek did to us, as [Deuteronomy 25:17] states: "Remember what Amalek did to you."