2 Samuel 18:23

by the way of the plain "The plain" (Heb. kikkar) is the technical term for the floor of the valley through which the Jordan runs. In our ignorance of the exact position of the battlefield, we cannot trace the routes taken by the rival runners with certainty. But in all probability what is meant is that Ahimaaz struck down into the Jordan valley, and ran by a longer but easier route to Mahanaim, while the Cushite took the direct but more difficult route over the hills.