Exodus 17:14-16

14The Lord then said to Moses, “Write this down on a scroll as a reminder and recite it to Joshua: I will completely blot out the memory of Amalek under heaven.”

15And Moses built an altar and named it, “The Lord Is My Banner.”

16He said, “Indeed, my hand is lifted up toward the Lord’s throne. The Lord will be at war with Amalek from generation to generation.”