From which mountain did King Abijah call out to Jeroboam and all Israel before battle?

Answer: Mount Zemaraim

Before his battle with Jeroboam, Abijah stood on Mount Zemaraim in the hill country of Ephraim and called out to Israel.

“Abijah went into battle with an army of 400,000 chosen men, while Jeroboam drew up in formation against him with 800,000 chosen and mighty men of valor. Then Abijah stood on Mount Zemaraim in the hill country of Ephraim and said, “Hear me, O Jeroboam and all Israel!”— 2 Chronicles 13:3-4 (BSB)