John Gill Commentary Proverbs 19:5

"A false witness shall not be unpunished; And he that uttereth lies shall not escape." — Proverbs 19:5 (ASV)

A false witness shall not be unpunished
He that bears false witness against his neighbour in an open court of judicature; though he may not be detected by men, and so escape the punishment due to such offenders by the laws of God and men; yet God, who knows all hearts and actions, will not suffer him to go with impunity; if not punished in this world, he shall be in the world to come; for bearing false witness, or perjury, is a grievous offence to God;

and [he that] speaks lies shall not escape ;
even he that uses himself to lying in private conversation shall not escape the reproach of men; for nothing is more scandalous than lying; nor the wrath of God, such shall have their portion in the lake which burns with fire and brimstone, (Revelation 21:8) .