Exodus 17:10-12 NIV

10 So Joshua fought the Amalekites as Moses had ordered, and Moses, Aaron and Hur1 went to the top of the hill.

References for Exodus 17:10

      11 As long as Moses held up his hands, the Israelites were winning,2 but whenever he lowered his hands, the Amalekites were winning.

      References for Exodus 17:11

      12 When Moses' hands grew tired, they took a stone and put it under him and he sat on it. Aaron and Hur held his hands up--one on one side, one on the other--so that his hands remained steady till sunset.3

      References for Exodus 17:12