John Gill's Exposition of the Whole Bible
Isaiah 32:4
The heart also of the rash shall understand knowledge,.... Such who have been hasty and precipitant, as the word c signifies; who have not given themselves time to consider what they have read or heard, or has been proposed unto them, and have hastily received every thing that has been suggested to them, especially by carnal sense and reason, shall now sit down, and coolly consider things, and so gain an understanding of divine and spiritual knowledge, of the knowledge of Christ, of his person, offices, grace, righteousness, and salvation; an experimental knowledge and understanding of these things, heart and not head knowledge:
and the tongue of the stammerer shall be ready to speak plainly; or, "shall make haste to speak neatly" d; elegantly and politely; such who hesitated in their speech, and spoke in a blundering manner, and scarcely intelligibly, especially when they spoke of divine and spiritual things, yet now, without the least hesitation, in the freest and most ready manner, with all plainness and propriety shall talk of these things, to the great delight, satisfaction, and use of those that hear them: this was true of the apostles of Christ, those babes and sucklings, out of whose mouth God ordained praise, and who were most of them Galilaeans, very illiterate and unpolished, and yet these, especially when they had the gift of tongues, spake the great things of God very readily, and in good language; and also is true of other ministers of the word, raised up among the barbarous nations of the world.
c נמהרים "inconsideratorum", Junius Tremellius, Piscator "praecipatorum", Montanus. d תמהר לדבר צחות "festinabit loqui nitida", Pagninus; "polite", Munster; "diserte", Calvin; "loqui venusta", Cocceius.