And it came to pass, when Moses held up his hand, that Israel prevailed: and when he let down his hand, Amalek prevailed. But Moses hands were heavy; and they took a stone, and put it under him, and he sat thereon; and Aaron and Hur stayed up his hands. Exodus 17:11

Trivia: What did a voice from heaven tell John to do with a little book that was in an angel's hand (Rev 10)?