Albert Barnes Commentary 2 Samuel 2:29

"And Abner and his men went all that night through the Arabah; and they passed over the Jordan, and went through all Bithron, and came to Mahanaim." — 2 Samuel 2:29 (ASV)

Through the plain - See 1 Samuel 23:24. The location of Bithron is unknown. From the expression “all Bithron,” it seems likely that it refers to a region of land on the east side of the Jordan, intersected by ravines.