Albert Barnes Commentary Judges 9:48

"And Abimelech gat him up to mount Zalmon, he and all the people that were with him; and Abimelech took an axe in his hand, and cut down a bough from the trees, and took it up, and laid it on his shoulder: and he said unto the people that were with him, What ye have seen me do, make haste, and do as I have done." — Judges 9:48 (ASV)

Zalmon - A lofty and thickly-wooded hill, as the etymology of the name (“shady”) implies, in the immediate neighborhood of Shechem: perhaps the same as Ebal. The setting fire to the hold, where the men of Shechem were all crowded together, with their wives and children, was the literal fulfillment of Jotham’s curse in Judges 9:20.