Or HaChaim on Numbers 21:14/אור החיים על במדבר כ״א:י״ד

1 על כן יאמר בספר מלחמות השם, wherefore it is said in the book of the Wars of the Lord, etc. Our sages offer two explanations on this verse, one in Kidushin 30 where they interpret the "wars" as referring to the disagreements between scholars about how to interpret the Torah. Such disagreements are called "a war of G'd," as these people are friendly with one another on a personal basis though opposing each other as Torah scholars. This is supposed to be the meaning of the words את והב בסופה. The second explanation is offered in Berachot 54 where the Talmud says that there were two Jews who had been stricken with Tzoraat one of whom was called את and the other והב. They trailed the remainder of the Israelite camp walking behind the main body seeing they were not allowed into the camp proper as מצורעים, people afflicted with this skin eczema. It was they who informed the others of the collision of the mountains situated on either side of the river Arnon.

2We prefer to explain this verse according to its plain meaning. The Torah mentioned in verse 13 that the river Arnon formed the boundary between Moav and the Emorite. It follows that Israel owned no part of it. This is the reason the Torah goes on to say that in the book which is open before G'd and which contains records of the various wars describing which nation G'd disinherited and to which nation He granted additional territory, the river Arnon is recorded as the border between Moav and the Emorite. It is also recorded in that book that eventually, i.e. בסופה, this area will become part of the land of Israel. However, the time had not come for this development. The area in question is part of the three tribes Keyni, Kenizi, and Kadmoni whose territory was included in G'd's promise to Abraham at the covenant of the pieces (Genesis 15,19) but whose territory Israel never conquered to this day.

3The word והב may have either of two meanings. 1) It is an expression of love, אהבה, i.e. that G'd loves to give these lands to Israel also but not at that time. 2) It is an expression denoting נתינה, giving, granting. We find this expression in that sense [aramaic, Ed.] in Daniel 2,23 "You have granted me wisdom." This is not the only time that the Torah employs aramaic words. Some other examples are Genesis 21,7 מי מלל; another example is Deut. 33,2 ואתא מרבבות קדש.

4The Torah continues ואת הנחלים, "and the brooks, etc.," to further describe in detail the borders of Moav which are recorded in the book in which G'd records the various wars. In the future all the tributaries of Arnon will become part of the land of Israel as well as the tributaries which are close to the seat of Or.