And Moses built an altar and named it The LORD Is My Banner.
15. And Moses built an altar. The purpose of this was that not he alone, but the whole people should testify, by solemn sacrifice, their gratitude; which the very name of the altar proves. For neither did he wish to erect a statue to God, nor to honor the altar by God’s name, but he shows that this was the object he proposed to himself...
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 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...