8 Then Amalek came and fought with Israel at Rephidim. 9 Moses said to Joshua, "Choose some men for us and go out, fight with Amalek. Tomorrow I will stand on the top of the hill with the staff of God in my hand." 10 So Joshua did as Moses told him, and fought with Amalek, while Moses, Aaron, and Hur went up to the top of the hill. 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.
Matthew Henry's Commentary on Exodus 17:8-13
Commentary on Exodus 17:8-16
(Read Exodus 17:8-16)
Israel engaged with Amalek in their own necessary defence. God makes his people able, and calls them to various services for the good of his church. Joshua fights, Moses prays, both minister to Israel. The rod was held up, as the banner to encourage the soldiers. Also to God, by way of appeal to him. Moses was tired. The strongest arm will fail with being long held out; it is God only whose hand is stretched out still. We do not find that Joshua's hands were heavy in fighting, but Moses' hands were heavy in praying; the more spiritual any service is, the more apt we are to fail and flag in it. To convince Israel that the hand of Moses, whom they had been chiding, did more for their safety than their own hands, his rod than their sword, the success rises and falls as Moses lifts up or lets down his hands. The church's cause is more or less successful, as her friends are more or less strong in faith, and fervent in prayer. Moses, the man of God, is glad of help. We should not be shy, either of asking help from others, or of giving help to others. The hands of Moses being thus stayed, were steady till the going down of the sun. It was great encouragement to the people to see Joshua before them in the field of battle, and Moses above them on the hill. Christ is both to us; our Joshua, the Captain of our salvation, who fights our battles, and our Moses, who ever lives, making intercession above, that our faith fail not. Weapons formed against God's Israel cannot prosper long, and shall be broken at last. Moses must write what had been done, what Amalek had done against Israel; write their bitter hatred; write their cruel attempts; let them never be forgotten, nor what God had done for Israel in saving them from Amalek. Write what should be done; that in process of time Amalek should be totally ruined and rooted out. Amalek's destruction was typical of the destruction of all the enemies of Christ and his kingdom.