Devarim/Deuteronomy  25:17 - 19

Chapter 25

¹⁷ Remember what Amalek did to you, on the way when you were leaving Egypt;  ¹⁸ that he happened upon you on the way, and he struck those of you who were hindmost, all the weaklings at your rear, when you were faint and exhausted, and he did not fear God.  ¹⁹ It shall be that when Hashem, your God, gives you rest from all your enemies all around, in the Land that Hashem, your God, gives you as an inheritance to possess it, you shall wipe out the memory of Amalek from under the heaven — you shall not forget!