Matthew Poole and continuators on Numbers 21:24

24 And Israel smote him with the edge of the sword, and possessed his land from Arnon unto Jabbok , even unto the children of Ammon, for the border of the children of Ammon was strong .

Or, which reached from Arnon, &c. such supplements being very usual, and so here is contained a description or limitation of Sihons conquest and kingdom, that it extended onely from Arnon▪—unto the children of Ammon, and then the following words, for the border of the children of Ammon was strong, come in very fitly, not as a reason why the Israelites did not or could not conquer the Ammonites, for they were absolutely forbidden to meddle with them, Deut. 3. 8. but as a reason why Sihon could not enlarge his conquest and empire to the Ammonites, as he had done to the Moabites.

A river by which the countries of Ammon and Moab were in part bounded and divided.

Either by the advantage of the river, or by their strong holds in their frontiers.

Marginal references: Deut. 2. 32. & 29. 7.; * Josh. 12. 2. & 24. 8. Psal. 135. 10, 11. & 136. 19. Amos 2. 9.