John Calvin Commentary Exodus 17:13

"And Joshua discomfited Amalek and his people with the edge of the sword." — Exodus 17:13 (ASV)

And Joshua discomfited Amalek. The connecting word 'And' is used here not merely as a simple link, but rather with the force of an illative particle (a word indicating a conclusion); for Moses here concludes that the Israelites overcame their enemies because he had continually persevered in prayer. There is also an implied antithesis between the firmness of his hands and the weakness of the enemy, so that we may understand that they were defeated or conquered not so much by the sword as by the uplifting of the rod and by the intercession of the holy man.