Numbers 21:4 - Joseph Benson’s Commentary on the Old and New Testaments

By the way of the Red sea The way which led to the Red sea, which they were under a necessity of taking, that they might compass the land of Edom. But as they had gained an advantage over the king of Arad, why did they not pursue their victory, and now enter Canaan? Because God would not permit it, there being several works yet to be done; other people must be conquered, the Israelites must be further humbled, tried, and purged, Moses must die, and then they shall enter, and that in a more glorious manner, even over Jordan, which shall be miraculously divided to give them passage. The soul of the people was much discouraged Or, they grew fretful and impatient, as the words import. Having met with so many difficulties and discouragements in their way to Canaan; particularly being now obliged, by the Edomites refusing to give them a passage through their country, to retire back southward, and thence again to turn eastward, and to take a round by the territories of the Moabites; they began to think they should never come to the promised land, and so fell into their old spirit of murmuring against God, and throwing reflections on Moses. They seem to have been the more excited to this by the successful entrance and victorious progress which some of them had made in the borders of Canaan; because they concluded from this that they might speedily have gone in and taken possession of it, and so have saved the tedious travels, and further difficulties, into which Moses had again brought them.