Exodus 17:14 - 17:16
14 Then Yahweh said to Moses, “Write this in a book as a memorial and recite it in Joshua’s hearing, that I will utterly blot out the memory of Amalek from under heaven.” 15 And Moses built an altar and named it Yahweh is My Banner; 16 and he said, “Because He has sworn with a hand upon the throne of Yah, Yahweh will have war against Amalek from generation to generation.”