Exodus 17:9-11

New Century Version

⁹ So Moses said to Joshua, “Choose some men and go and fight the Amalekites. Tomorrow I will stand on the top of the hill, holding the walking stick of God in my hands.”

¹⁰ Joshua obeyed Moses and went to fight the Amalekites, while Moses, Aaron, and Hur went to the top of the hill. ¹¹ As long as Moses held his hands up, the Israelites would win the fight, but when Moses put his hands down, the Amalekites would win.