A man shall eat good by the fruit of his mouth.
Natural retaliation
Although the spirit and practice of retaliation are nowhere vindicated in Scripture, but everywhere explicitly and strongly condemned, yet a treatment corresponding to their own conduct towards others is what every one may expect. In the nature of things it cannot be otherwise. It is not in human nature, nor in any nature, not even in the Divine itself, to love with the love of complacence that which is unamiable. An amiable disposition alone can secure love; and amiability of disposition is greatly indicated by the tongue. The man who is charitable in his judgments, and disposed to speak well of others, will be himself the subject of charitable judgment and of cordial commendation. All will love and honour and bless the man “in whose tongue is the law of kindness.” Thus he shall “eat good by the fruit of his mouth.” On the contrary, against the man who is a “transgressor” with his lips, making them the instruments of malice in the utterance of slander, and the fomenting of alienation and strife--against that man are unavoidably kindled all the feelings of indignation, all the angry passions, of which the result is violence--the violence of vindictive pride and sense of wrong. (R. Wardlaw.)
Man speaking
Here are several kinds of speech.
I. The self-profiting and self-ruinous in speech. The speech of a good man which is enlightened, truthful, pure, generous, is of service to himself in many ways. By it he promotes the development of his own spiritual being, he gratifies his own moral nature, and produces in hearers results which are delightful to his own observation. The corrupt speech of the ungodly is a violence to reason, conscience, social propriety. The sinful tongue of the transgressor inflicts the most violent injuries on his own nature.
II. The self-controlled and the self-reckless in speech.
1. Controlled speech may be useful. The tongue is a member that requires controlling. Passion and impulse are constantly stimulating it to action.
2. Reckless speech may be dangerous. One spark from a lawless tongue has often kindled conflagrations in families, churches, and nations. Quarles says, “Give not thy tongue too much liberty, lest it take thee prisoner.” (D. Thomas, D.D.)
A guard upon the lips
is a guard to the soul. He that keeps a strong bridle on his tongue, and a strong hand on that bridle, keeps his soul from a great deal, both of guilt and grief, and saves himself the trouble of many bitter reflections on himself, and reflections of others upon him. There is many a one ruined by an ungoverned tongue. He that loves to bawl and bluster and make a noise, will find it will be the destruction of his reputation, his interest, and his comfort. (Matthew Henry.)