Commentaries
31:6-9 They have been backsliding children, yet children; let them return, and their backslidings shall be healed, though they have sunk deep into misery, and cannot easily recover. Many make an idol of their silver and gold, and by the love of that are drawn from God; but those who turn to God, will be ready to part with it. Then, when they have cast away their idols, shall the Assyrian fall by the sword of an angel, who strikes more strongly than a mighty man, yet more secretly than a mean man. God can make the stoutest heart to tremble. But if we keep up the fire of holy love and devotion in our hearts and houses, we may depend upon God to protect us and them.
9. Rather, "shall pass beyond his strongholds"; he Shall not stop to take refuge in it through fear (Jud 20:47; Jer 48:28) [Gesenius].
ensign—the banner of Jehovah protecting the Jews [Maurer].
fire … furnace—"light" and "fire," namely, of Jehovah's altar at Jerusalem (Isa 29:1). Perhaps "furnace," as distinguished from "fire," may mean that His dwelling-place (His hearth) was at Jerusalem (compare Isa 4:5); or else the fiery furnace awaiting all the enemies who should attack Jerusalem.