Exodus 17:9 DBY

⁷  And he called the name of the place Massah, and Meribah, because of the contention of the children of Israel, and because they had tempted Jehovah, saying, Is Jehovah among us, or not?

⁸  And Amalek came and fought with Israel in Rephidim.

⁹  And Moses said to Joshua, Choose us men, and go out, fight with Amalek; to-morrow I will stand on the top of the hill with the staff of God in my hand.

¹⁰  And Joshua did as Moses had said to him, to fight with Amalek; and Moses, Aaron and Hur went up to the top of the hill.

¹¹  And it came to pass when Moses raised his hand, that Israel prevailed; and when he let down his hand, Amalek prevailed.