John Calvin Commentary Numbers 21:10

"And the children of Israel journeyed, and encamped in Oboth." — Numbers 21:10 (ASV)

And the children of Israel set forth. Moses does not enumerate all the stations here, which will be mentioned later when he reviews them all separately and in order. For, in hastening to record certain memorable circumstances, he passes over those of minor importance.

These details, however, he does not omit elsewhere; since the account of their circuitous course, when they were turning away from the Edomites, was of some importance. For it was, as we have observed, no ordinary proof of obedience that, when God had forbidden them to attack the Edomites, they undertook a difficult and rugged march.

Still, in this place, Moses considered it sufficient to mark the principal places where they stopped. Meanwhile, it appears to be as I have stated: he hastens onward to relate circumstances of great importance, for when they came to Arnon, he highly magnifies the power of God, with which He helped His people.