The following admonitions of this chapter bear reference to the outward conduct of life. They continue the subject of Proverbs 4:23 by showing how the guarding of the heart is to be done. There is the most; intimate connection between the heart as the fountain of the moral life and of the conduct of life, which, though determined by the condition of the heart, in its turn reacts upon the heart as the moral centre, and keeps it pure.
Thus the subject is treated from its two sides. On Proverbs 4:24 and Proverbs 4:25 Hitzig remarks that they "warn against an arbitrary perverting of the moral judgment into which evil passions so easily betray, and admonish not to give misdirection to thought within the department of morality."
A froward mouth, and perverse lips; literally, perverseness of mouth and waywardness of lips (ikk'shuth peh vulzuth s'phathayim). "Perversity of mouth" is fraudulent, deceitful speech; that which twists, distorts, perverts, or misrepresents what is true, and hence falsehood (Proverbs 4:24; Proverbs 6:12; Proverbs 19:1).
The σκολιὸν στόμα of the LXX; i.e. the "tortuous mouth," in a metaphorical sense. The phrase is very similar in meaning with the parallel "waywardness of lips," which means speech which turns aside from what is true and right, the noun lazuth being derived from lazah, or luz, "to bend aside."
The tongue is the unruly member (James 3:2). Speech is the index of the mind (Lapide). Vigilance over the heart is vigilance over the mouth, inasmuch as "out of the abundance of the heart the mouth speaketh" (Matthew 12:34).
The admonition may have a twofold application, and may mean either do not indulge in this kind of speech yourself, exercise an unremitting jealousy over every propensity to it; or have no dealings with those who are guilty of it, as in Psalms 101:5.