Exodus 17:13-15

Young's Literal Translation

¹³ and Joshua weakeneth Amalek and his people by the mouth of the sword.

¹⁴ And Jehovah saith unto Moses, `Write this, a memorial in a Book, and set [it] in the ears of Joshua, that I do utterly wipe away the remembrance of Amalek from under the heavens;'

¹⁵ and Moses buildeth an altar, and calleth its name Jehovah-Nissi,