Charles Ellicott Commentary Numbers 21:4

"And they journeyed from mount Hor by the way to the Red Sea, to compass the land of Edom: and the soul of the people was much discouraged because of the way." — Numbers 21:4 (ASV)

Because of the way— Better, in (or, on) the way. In addition to all the hardships and dangers of the journey, they were conscious that they were turning their backs upon the land of Canaan, instead of marching by a direct course into it.