Charles H. Spurgeon on Psalms 21:9

"Thou shalt make them as a fiery oven in the time of thine anger." They shall not only be cast into a furnace of fire (Matthew 13:42), but he shall make them themselves as a fiery oven or furnace, they shall be their own tormentors, the reflections and terrors of their own consciences will be their hell. Those that might have had Christ to rule and save them, but rejected him, and fought against him, even the remembrance of that will be enough to make them to eternity a fiery oven to themselves. —Matthew Henry.