Exodus 17
10 Ref So Joshua did as Moses said to him, and went to war with Amalek: and Moses, Aaron, and Hur went up to the top of the hill.
11 Ref Now while Moses' hand was lifted up, Israel was the stronger: but when he let his hand go down, Amalek became the stronger.
12 Ref But Moses' hands became tired; so they put a stone under him and he took his seat on it, Aaron and Hur supporting his hands, one on one side and one on the other; so his hands were kept up without falling till the sun went down.