Exodus 17:14-16

14The Lord said to Moses, “Write this as a memorial in the book, and rehearse it in Joshua’s hearing; for I will surely wipe out the remembrance of Amalek from under heaven.

15Moses built an altar, and he called it “The Lord is my Banner,”

16for he said, “For a hand was lifted up to the throne of the Lord – that the Lord will have war with Amalek from generation to generation.”