Jeremiah 23:29 - Ellicott's Commentary On The Whole Bible

Is not my word like as a fire?... — The prophet speaks out of the depths of his own experience. The true prophetic word burns in the heart of a man, and will not be restrained (Jeremiah 5:14; Jeremiah 20:9; Psalms 39:3), and when uttered it consumes the evil, and purifies the good. It will burn up the chaff of the utterances of the false prophets. (Comp. 1 Corinthians 3:12-13.) As the hammer breaks the rock, so it shatters the pride and stubbornness of man, is mighty to the pulling down of strongholds (2 Corinthians 10:4), and the heart of him who hears it as it should be heard is broken and contrite. What these words paint in the language of poetry, St. Paul describes without imagery in 1 Corinthians 14:24-25. (Comp. also Hebrews 4:12.)