(15) Moses built an altar.--Primarily, no doubt, to sacrifice thank-offerings upon it, as an acknowledgment of the Divine mercy in giving Israel the victory. But secondarily as a memorial--a monument to commemorate Israel's triumph.

And called the name of it Jehovah-nissi.--Jacob had named an altar "El-Elohe-Israel" (Genesis 33:20); but otherwise we do not find altars given special names. When an altar was built as a memorial, the purpose would be helped by a name, which would tend to keep the event commemorated in remembrance. Jehovah-nissi--"the Lord is my banner"--would tell to all who heard the word that here there had been a struggle, and that a people which worshipped Jehovah had been victorious. It is not clear that there is any reference to "the rod of God" (Exodus 17:9) as in any sense the "banner" under which Israel had fought. The banner is Jehovah Himself, under whose protection Israel had fought and conquered.

Verse 15. - Moses built an altar. An altar naturally implies a sacrifice, and Moses may well have thought that the signal victory obtained required to be acknowledged, and as it were requited, by offerings. In giving his altar a name, he followed the example of Jacob, who called an altar which he built, El-Elohe-Israel (Genesis 33:20). Moses' name for his altar, Jehovah-nisi, meant "the Lord is my banner," and was intended to mark his ascription of the entire honour of the victory to Jehovah but had probably no reference to the particular mode in which the victory was gained.

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.And Moses built an altar,.... On Horeb, as Aben Ezra; on the top of the hill, as Ben Gersom, where sacrifices of thanksgiving were offered up for the victory obtained, or however a monument erected in memory of it:

and he called the name of it Jehovahnissi; which signifies either "the Lord is my miracle" who wrought a miracle for them in giving them the victory over Amalek, as well as, through smiting the rock with the rod, brought out water from thence for the refreshment of the people, their children and cattle; or "the Lord is my banner": alluding to the hands of Moses being lifted up with the rod therein, as a banner displayed, under which Joshua and Israel fought, and got the victory. This may fitly be applied to Christ, who is both altar, sacrifice, and priest, and who is the true Jehovah, and after so called; and who is lifted up as a banner, standard, or ensign in the everlasting Gospel, in order to gather souls unto him, and enlist them under him, and to prepare them for war, and encourage them in it against their spiritual enemies; and as a token of their victory over them, and a direction to them where they shall stand, when to march, and whom they shall follow; and to distinguish them from all other bands and companies, and for the protection of them from all their enemies, see Isaiah 11:10. These words were inscribed upon the altar, or the altar was called the altar of Jehovahnissi, in memory of what was here done; from hence it has been thought (a), that Baachus, among the Heathens, had his name of Dionysius, as if it was Jehovahnyssaeus.

(a) Vid. Bochart. Canaan, l. 1. c. 18. col. 440.