As long as Moses held up his hands, Israel prevailed; but when he lowered them, Amalek prevailed.
We have here the story of the war with Amalek, which, we may suppose, was the first that was recorded in the book of the wars of the Lord, Num 21:14. Amalek was the first of the nations that Israel fought with, Num 24:20. Observe, I. Amalek's attempt: They came out, and fought with Israel, Exo 17:8.
Commenting on Exodus 17:8-16
And it came to pass, when Moses held up his hand, that Israel prevailed,.... With his rod in it as a banner displayed, as some think, which inspired the Israelites with courage to fight, and they had the better of it; though Aben Ezra rejects that notion, observing, that if that had been the case, Aaron or Hur would have lifted it up, or fixed...
ATTACK OF AMALEK. (Exo 17:8-16) Then came Amalek--Some time probably elapsed before they were exposed to this new evil; and the presumption of there being such an interval affords the only ground on which we can satisfactorily account for the altered, the better, and former spirit that animated the people in this sudden contest.
Commenting on Exodus 17:8-16