Deuteronomy 25:17-19

17“Never forget what the Amalekites did to you as you came from Egypt.

18They attacked you when you were exhausted and weary, and they struck down those who were straggling behind. They had no fear of God.

19Therefore, when the Lord your God has given you rest from all your enemies in the land he is giving you as a special possession, you must destroy the Amalekites and erase their memory from under heaven. Never forget this!