Hur A person of eminence, no doubt, but who he was is uncertain. Josephus, however, tells us, he was the husband of Miriam, Antiq., 50:3, chap. 2. And when Moses held up his hand in prayer (so the Chaldee explains it) Israel prevailed: but when he let down his hand from prayer Amalek prevailed To convince Israel that the hand of Moses (with whom they had just now been chiding) contributed more to their safety than their own hands; the success rises and falls, as Moses lifts up or lets down his hand. The Church's cause is ordinarily more or less successful, according as the Church's friends are more or less fervent in prayer.
Related Commentaries of Exodus 17:10
Exodus 17:10-11
10 So Joshua did as Moses had said to him, and fought with Amalek: and Moses, Aaron, and Hur went up to the top of the hill.
11 And it came to pass, when Moses held up his hand, that Israel prevailed: and when he let down his hand, Amalek prevailed.