Sion must not be confounded with Zion (compare Psalm 48:2.).

From Aroer, which is by the bank of the river Arnon,.... A city of Moab, which was situated on the bank of the river Arnon, that was on the border of Moab, Deuteronomy 2:36,

even unto Mount Sion, which is Hermon; the meaning is, that the lands of these two kings conquered by Israel reached from the city Aroer on the river Arnon to Mount Hermon, the one being the southern, the other the northern boundary of them. Here Hermon has another name Sion, and is to be carefully distinguished from Mount Zion near Jerusalem; it lying in a different country, and being written with a different letter in the Hebrew language. In the Septuagint version it is called Seon, and by the Targums of Jonathan and Jerusalem the mount of snow; See Gill on Deuteronomy 3:9.

From Aroer, which is by the bank of the river Arnon, even unto mount Sion, which is Hermon,

4:41-49 Here is the introduction to another discourse, or sermon, Moses preached to Israel, which we have in the following chapters. He sets the law before them, as the rule they were to work by, the way they were to walk in. He sets it before them, as the glass in which they were to see their natural face, that, looking into this perfect law of liberty, they might continue therein. These are the laws, given when Israel was newly come out of Egypt; and they were now repeated. Moses gave these laws in charge, while they encamped over against Beth-peor, an idol place of the Moabites. Their present triumphs were a powerful argument for obedience. And we should understand our own situation as sinners, and the nature of that gracious covenant to which we are invited. Therein greater things are shown to us than ever Israel saw from mount Sinai; greater mercies are given to us than they experienced in the wilderness, or in Canaan. One speaks to us, who is of infinitely greater dignity than Moses; who bare our sins upon the cross; and pleads with us by His dying love.