8 Then came Amalek and fought with Israel at Rephidim. 9 And Moses said to Joshua, “Choose for us 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 told him, and fought with Amalek; and Moses, Aaron, and Hur went up to the top of the hill. 11 Whenever Moses held up his hand, Israel prevailed; and whenever he lowered his hand, Amalek prevailed. 12 But Moses’ hands grew weary; so they took a stone and put it under him, and he sat upon it, and Aaron and Hur held up his hands, one on one side, and the other on the other side; so his hands were steady until the going down of the sun. 13 And Joshua mowed down Amalek and his people with the edge of the sword.

14 And the Lord said to Moses, “Write this as a memorial in a book and recite it in the ears of Joshua, that I will utterly blot out the remembrance of Amalek from under heaven.” 15 And Moses built an altar and called the name of it, The Lord is my banner, 16 saying, “A hand upon the banner of the Lord! The Lord will have war with Amalek from generation to generation.”