Charles Ellicott Commentary 2 Chronicles 13:4

"And Abijah stood up upon mount Zemaraim, which is in the hill-country of Ephraim, and said, Hear me, O Jeroboam and all Israel:" — 2 Chronicles 13:4 (ASV)

And Abijah stood up upon mount Zemaraim. — While the two hosts were facing each other, King Abijah addressed his foes from Mount Zemaraim, as Jotham addressed the Shechemites from the top of Mount Gerizim in the days of the judges (Judges 9:7).

Upon. — Literally, from upon to Mount Zemaraim; a mark of the Chronicler’s hand.

Mount Zemaraim is otherwise unknown. A city so-called is mentioned (Joshua 18:22) as near Bethel, and probably lay a little to the south of it, on the northern frontier of Judah, perhaps on this mountain.

Mount Ephraim. — The hill country of Ephraim.