The forest — By the forest he either means the forest of Lebanon or their houses, made of wood cut out of that forest. And it — And this fire shall not end in the destruction of this city, but in the total destruction of all the country round Jerusalem.
Related Commentaries of Jeremiah 21:14
Jeremiah 21:14
14 But I will punishc you according to the fruit of your doings, saith the LORD: and I will kindle a fire in the forest thereof, and it shall devour all things round about it.