Charles Ellicott Commentary Isaiah 32:4

"And the heart of the rash shall understand knowledge, and the tongue of the stammerers shall be ready to speak plainly." — Isaiah 32:4 (ASV)

The heart also of the rash ... —“Heart,” as in Proverbs 4:23 and elsewhere, signifies the intellect rather than the emotions. The “rash” are those who are “hurried,” precipitate, reckless; the “stammerers” are those who have no power to speak clearly of the things of God, who hesitate and are undecided.