Deuteronomy 25:17-19

17“Remember what Amalek did to you on the way as you were coming out of Egypt,

18how he met you on the way and attacked your rear ranks, all the stragglers at your rear, when you were tired and weary; and he did not fear God.

19Therefore it shall be, when the Lord your God has given you rest from your enemies all around, in the land which the Lord your God is giving you to possess as an inheritance, that you will blot out the remembrance of Amalek from under heaven. You shall not forget.