8 Then came Amalek [descendants of Esau] and fought with Israel at Rephidim. 9 And Moses said to Joshua, Choose us out men and go out, fight with Amalek. Tomorrow I will stand on the top of the hill with the rod of God in my hand. 10 So Joshua did as Moses said and fought with Amalek; and Moses, Aaron, and Hur went up to the hilltop. 11 When Moses held up his hand, Israel prevailed; and when he lowered his hand, Amalek prevailed. 12 But Moses' hands were heavy and grew weary. So [the other men] took a stone and put it under him and he sat on it. Then Aaron and Hur held up his hands, one on one side and one on the other side; so his hands were steady until the going down of the sun. 13 And Joshua mowed down and disabled Amalek and his people with the sword.
14 And the Lord said to Moses, Write this for a memorial in the book and rehearse it in the ears of Joshua, that I will utterly blot out the remembrance of Amalek from under the heavens. 15 And Moses built an altar and called the name of it, The Lord is my Banner; 16 And he said, Because [theirs] is a hand against the throne of the Lord, the Lord will have war with Amalek from generation to generation.