Exodus 17:11-13

New Revised Standard Version, Anglicised Catholic Edition

¹¹ Whenever Moses held up his hand, Israel prevailed; and whenever he lowered his hand, Amalek prevailed. ¹² But Moses’ hands grew weary; so they took a stone and put it under him, and he sat on it. Aaron and Hur held up his hands, one on one side, and the other on the other side; so his hands were steady until the sun set. ¹³ And Joshua defeated Amalek and his people with the sword.