John Gill's Exposition of the Whole Bible
Proverbs 15:2
The tongue of the wise useth knowledge aright,.... As the heart of a wise and good man is filled with useful knowledge, civil, moral, spiritual, and evangelical; so he takes care to communicate it, at proper times and seasons, in proper places, and to proper persons; adapting it to their case and circumstances, so as it may be for their comfort, edification, and instruction, and minister grace unto them; which is using knowledge "well", as the word s signifies: such an use of it recommends it, and makes it appear beautiful and lovely, decorates and adorns it. Thus every good man, out of the good treasure of knowledge in his heart, brings forth his good things seasonably, to the use of edifying; in like manner, ministers of the word, scribes well instructed in the things of God, bring forth both new and old, to the profit of those to whom they minister; so Christ, as man and Mediator, had the tongue of the learned, to speak a word in season to weary souls;
but the mouth of fools poureth out foolishness; their knowledge, as they take it to be, but it is no other than folly; this they throw out in great plenty, in a hurry, without fear or wit; they "babble" it out, as the word t signifies, as water out of a fountain; their hearts are full of it, and their mouths proclaim it, Proverbs 12:23.
s היטיב "utitur bene", Castalio; "pulchre", Vatablus. t יביע "effutit, ebullit, fundit", Vatablus; "eructat", Junius Tremellius, Piscator "ebullit", V. L. Tigurine version, Schultens; "scaturire facit", Michaelis.