Exodus 17:11

For in this way, when the eyes are lifted up through thought and contemplation and the hands are lifted up in deeds which lift up and exalt the soul, as Moses lifted up his hands, one may consequently say, "The lifting up of my hands is as the evening sacrifice." In this way the Amalekites and all the unseen enemies will be worsted, and the Israelite reasonings in us will prevail.

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 it in a high place on the mount, that it might have been seen standing; and therefore he thinks the sense of the ancients the most correct, that it was a prayer gesture.

And when Moses held vp 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.

Even the best cause must expect disappointments as an alloy to its successes; though the battle be the Lord's, Amalek may prevail for a time. The reason was, Moses let down his hands. Note, The church's cause is, commonly, more or less successful according as the church's friends are more or less strong in faith and fervent in prayer.

When Moses held up his hand - We cannot understand this transaction in any literal way; for the lifting up or letting down the hands of Moses could not, humanly speaking, influence the battle. It is likely that he held up the rod of God in his hand, Exo 17:9, as an ensign to the people. We have already seen that in prayer the hands were generally lifted up and spread out, (See Clarke’s note on Exo 9:29), and therefore it is likely that by this act prayer and supplication are intended. The Jerusalem Targum says, “When Moses held up his hands in prayer, the house of Israel prevailed; and when he let down his hands from prayer, the house of Amalek prevailed.” We may therefore conclude, that by holding up the hands in this case these two things were intended: 1. That hereby a reference was made to God, as the source whence all help and protection must come, and that on him alone they must depend. 2. That prayer and supplication to God are essentially necessary to their prevalence over all their enemies. It is indisputably true that, while the hands are stretched out, that is, while the soul exerts itself in prayer and supplication to God, we are sure to conquer our spiritual adversaries; but if our hands become heavy - if we restrain prayer before God, Amalek will prevail - every spiritual foe, every internal corruption, will gain ground. Several of the fathers consider Moses, with his stretched-out hands, as a figure of Christ on the cross, suffering for mankind, and getting a complete victory over sin and Satan.