(Proverbs 19:9 KJV) A false witness shall not be unpunished, and he that speaketh lies shall perish.
A liar “speaketh” (tells NASB) (6315) lies. That would seem obvious but the word goes deeper than that. My NASB has a marginal note that says the word means “breaths”. That is much closer to the meaning. We have all met people like this. We joke about looking to see if the sun is up when someone tells us it is noon. They breathe deception.
It is generally a negative term. Out of fifteen times the Hebrew word is used I found four times it could be considered posititive and three of those were in the Song of Solomon where it was romantic.
This is a warning. It is not just saying “Don’t lie”. It is saying that destruction is waiting for you if you do.
So? Liars are destructive to the people around them. That is bad enough. They also are destroying themselves.