He will clear the forest thickets with an axe, and Lebanon will fall before the Mighty One.
34. And he will cut down the thick places of the forest with iron. There is no difficulty in explaining this metaphor, for it is plain enough that by tall and high trees is denoted all that is powerful, excellent, or lofty.
The prophet, in his preaching, distinguishes between the precious and the vile; for God in his providence, even in the same providence, does so. He speaks terror, in Sennacherib's invasion, to the hypocrites, who were the people of God's wrath, Isa 10:6. But here he speaks comfort to the sincere, who were the people of God's love.
Commenting on Isaiah 10:24-34
This verse and Isa 10:33 describe the sudden arrest and overthrow of Sennacherib in the height of his success; Isa 10:18-19; Eze 31:3, Eze 31:14, &c., contain the same image; "Lebanon" and its forest are the Assyrian army; the "iron" axe that fells the forest refers to the stroke which destroyed the one hundred and eighty-five thousand Assyrians (Kg2 19:35). The "Mighty One" is Jehovah (Isa 10:21; Isa 9:6).