The plain - The floor of the valley through which the Jordan runs. The Cushite did not run by that road, but took the road over the hills, which may well have been the shorter but also the more difficult road. The two roads would probably meet a short distance from Mahanaim. These words, which have been thought to prove that the battle took place on the west of Jordan, are a clear proof that it took place on the east, because if the runners had had to cross the Jordan, they must both have come by the same road, which it is clear they did not.
Related Commentaries of 2 Samuel 18:23
2 Samuel 18:23
23 But howsoever, said he, let me run. And he said unto him, Run. Then Ahimaaz ran by the way of the plain, and overran Cushi.