Charles Ellicott 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 (or the Arabah). —The wilderness of Gibeon lay to the east of the town, and Abner’s flight had thus carried him towards the Jordan. He now passed up the valley of the Jordan (which the word here used generally designates), and, crossing at a ford, went through all Bithron to Mahanaim. Bithron is evidently the name of a district on the east of the Jordan, but is not further known.