Exodus 17:14-16

14And Yhwh said unto Moses, Write this for a memorial in a book, and rehearse it in the ears of Joshua: for I will utterly put out the remembrance of Amalek from under heaven.

15And Moses built an altar, and called the name of it Jehovah–nissi, Yhwh Our Banner:1

16For he said, Because Yah hath sworn that Yhwh will have war with Amalek from generation to generation.23