John Gill's Exposition of the Whole Bible
Proverbs 17:4
A wicked doer giveth heed to false lips,.... A man of an ill spirit, of a mischievous disposition, that delights in doing wickedness; he carefully attends to such as speak falsehood; he listens to lies and calumnies, loves to hear ill reports of persons, and takes pleasure in spreading them to the hurt of their characters; and men of bad hearts and lives give heed to seducing spirits, to false teachers, to inch as speak lies in hypocrisy, who sooth and harden them in their wickedness;
[and] a liar giveth ear to a naughty tongue: or, "to a tongue of destruction" a; a culumniating, backbiting tongue, which destroys the good name and reputation of men; and he that is given to lying is made up of lying, or is a lie itself, as the word signifies; who roves and makes a lie, as antichrist and his followers; such an one hearkens diligently to everything that may detract from the character of those especially he bears an ill will to: or it may be better rendered, "he that hearkens to a lie [gives heed] to a naughty tongue" b; for a lying tongue is a naughty one, evil in itself, pernicious in its effects and consequences.
a על לשון הות "perniciosae linguae", Tigurine version; "linguae confractionum calamitatum, injuriarum", Vatablus; "ad linguam exiliorum", Michaelis. b So Michaelis.