| Barnes' Notes on the Bible Contrast the "studying" of the wise before he answers and the hasty babbling of the foolish. The teaching of our Lord Matthew 10:19 presents us with a different and higher precept, resting upon different conditions.
Clarke's Commentary on the BibleThe heart of the righteous studieth to answer - His tongue never runs before his wit, he never speaks rashly, and never unadvisedly; because he studies - ponders, his thoughts and his words.
Gill's Exposition of the Entire BibleThe heart of the righteous studieth to answer,.... He thinks before he speaks, meditates what he shall say, what answer to give to men; whether in things civil, natural, or religious; and what to return to the Lord when he is reproved by him; or what to say in prayer to him, or by way of thankfulness for mercies received from him; see Proverbs 3:6; though our Lord advises his disciples, when summoned before their persecutors, not to meditate beforehand what they should answer, since they should have immediate assistance, Luke 21:14; but this was in extraordinary cases; in common ones the observation of the wise man should be attended to. A Jewish (u) writer renders the words, "the heart of the righteous meditates wormwood", or bitter things; see Proverbs 5:4; as the judgment of God, death, and hell; this sense is mentioned by Aben Ezra, but rejected; but the mouth of the wicked poureth out evil things; without any previous thought and consideration, without fear or wit; in great abundance, as water out of a fountain; thus an evil man out of the evil treasure of his heart brings forth evil things readily and at once, having no concern about the consequences of things, Matthew 12:25; See Gill on Proverbs 15:2. (u) Kabvenaki.
Keil and Delitzsch Biblical Commentary on the Old TestamentTwo proverbs regarding the righteous and the wicked: 28 The heart of the righteous considereth how to answer right, And the mouth of the godless poureth forth evil. Instead of לענות, the lxx (Syr. and Targ.) imagines אמוּנות πίστεις; Jerome translates, but falsely, obedientiam (from ענה, to bend oneself); Meri thinks on לענה, wormwood, for the heart of the righteous revolves in itself the misery and the vanity of this present life; Hitzig corrects this verse as he does the three preceding: the heart of the righteous thinks on ענוות, a plur. of verb ענוה, which, except in this correction, does not exist. The proverb, as it stands, is, in fineness of expression and sharpness of the contrast, raised above such manglings. Instead of the righteous, the wise might be named, and instead of the godless, fools (cf. 2b); but the poet places the proverb here under the point of view of duty to neighbours. It is the characteristic of the righteous that he does not give the reins to his tongue; but as Luther has translated: the heart of the righteous considers [tichtet from dictare, frequently to speak, here carefully to think over] what is to be answered, or rather, since מה־לּענות is not used, he thinks thereupon to answer rightly, for that the word ענות is used in this pregnant sense is seen from 23a. The godless, on the contrary, are just as rash with their mouth as the righteous are of a thoughtful heart: their mouth sputters forth (effutit) evil, for they do not first lay to heart the question what may be right and just in the case that has arisen.
Geneva Study BibleThe heart of the righteous studieth to answer: but the mouth of the wicked poureth out evil things.
Wesley's Notes 15:28 Studieth - He speaks considerately. The mouth - Not the heart; for he rashly speaks what comes into his mouth, without the direction of his heart or conscience.
Jamieson-Fausset-Brown Bible Commentary28. (Compare Pr 15:14; 10:11). Caution is the fruit of wisdom; rashness of folly.
Matthew Henry's Concise Commentary15:25. Pride is the ruin of multitudes. But those who are in affliction God will support. 26. The thoughts of wicked men offend Him who knows the heart. 27. The covetous man lets none of his family have rest or enjoyment. And greediness of gain often tempts to projects that bring ruin. 28. A good man is proved to be a wise man by this; he governs his tongue well.
Matthew Henry's Whole Bible CommentaryVerse 28 Here is, 1. A good man proved to be a wise man by this, that he governs his tongue well; he that does so the same is a perfect man, Jam. 3:2. It is part of the character of a righteous man that being convinced of the account he must give of his words, and of the good and bad influence of them upon others, he makes conscience of speaking truly (it is his heart that answers, that is, he speaks as he thinks, and dares not do otherwise, he speaks the truth in his heart, Ps. 15:2), and of speaking pertinently and profitably, and therefore he studies to answer, that his speech may be with grace, Neh. 2:4; 5:7. 2. A wicked man is proved to be a fool by this, that he never heeds what he says, but his mouth pours out evil things, to the dishonour of God and religion, his own reproach, and the hurt of others. Doubtless that is an evil heart which thus overflows with evil. | 
