Exodus 17:15

13Joshua defeated Amalek and his people with the edge of the sword.

14The LORD said to Moses, “Write this for a memorial in a book, and rehearse it in the ears of Joshua: that I will utterly blot out the memory of Amalek from under the sky.”

15Moses built an altar, and called its name “The LORD our Banner”.

16He said, “The LORD has sworn: ‘The LORD will have war with Amalek from generation to generation.’”