Matthew Henry and continuators on Proverbs 19:5

5 A false witness shall not be unpunished, and he that speaketh lies shall not escape.

Here we have, 1. The sins threatened—bearing false witness in judgment and speaking lies in common conversation. Men could not arrive at such a pitch of impiety as to bear false witness (where to the guilt of a lie is added that of perjury and injury) if they had not advanced to it by allowing themselves to speak untruths in jest and banter, or under pretence of doing good. Thus men teach their tongues to speak lies, Jer. ix. 5. Those that will take a liberty to tell lies in discourse are in a fair way to be guilty of the greater wickedness of false-witness-bearing, whenever they are tempted to it, though they seemed to detest it. Those that can swallow a false word debauch their consciences, so that a false oath will not choke them. 2. The threatening itself: They shall not go unpunished; they shall not escape. This intimates that that which emboldens them in the sin is the hope of impunity, it being a sin which commonly escapes punishment from men, though the law is strict, Deut. xix. 18, 19. But it shall not escape the righteous judgment of God, who is jealous, and will not suffer his name to be profaned; we know where all liars will have their everlasting portion.