John Gill's Exposition of the Whole Bible
Proverbs 21:23
Whoso keepeth his mouth and his tongue,.... Guards the one and bridles the other; is careful of what he says, that it is truth, and without dissimulation and guile; and is not injurious to the characters of men, and is not offensive and provoking; who abstains from ill and wrathful language, and which tends to stir up wrath and contention. Aben Ezra distinguishes between the mouth and tongue, and interprets it, that keeps his mouth from eating, that is, immoderately and intemperately; and his tongue from speaking evil: but it is best to understand both of the same thing, of speech or language, which when a man is careful of, he
keepeth his soul from troubles; his conscience clear of guilt and distress, and his person from being concerned in quarrels, contentions, and lawsuits, which such who give their tongues too much liberty are involved in.