John Gill Bible Commentary

And shall cast them into a furnace of fire,.... Not a material, but a metaphorical one; denoting the wrath of God, which shall fall upon wicked men, and abide upon them to all eternity: which is sometimes called hell fire, sometimes a lake which burns with fire and brimstone; and here a furnace of fire, expressing the vehemency and intenseness of divine wrath, which will be intolerable; in allusion either to Nebuchadnezzar's fiery furnace, or as some think, to the custom of burning persons alive in some countries; or rather, to the burning of chaff and stubble, and the stalks of any unprofitable things that grew in the field (f), for the heating of furnaces, and is the very language of the Jews, who used to compare hell to a furnace; so Gen 15:17 is paraphrased by them (g), "And behold the sun set, and there was darkness; and lo! Abraham saw until the seats were set, and the thrones cast down; and lo! "hell", which is prepared for the wicked in the world to come, "as a furnace", which sparks and flames of fire surrounded; "in the midst of which", the wicked fell, because they rebelled against the law, in their lifetime. Which is expressed in much the same language, and conveys the same ideas as here; and no wonder is it that it follows, there shall be wailing and gnashing of teeth; declaring the remorse of conscience, the tortures of mind, the sense of inexpressible pain, and punishment, the wicked shall feel; also their furious rage and black despair, (f) Misn. Sabbat. c. 3. sect. 1. & Maimon, & Bartenora in ib. (g) Hieros. Targum in Gen. xv. 17.