(Proverbs 20:19 KJV) He that goeth about as a talebearer revealeth secrets: therefore meddle not with him that flattereth with his lips.
This is actually a bit of simple warning. If someone is sharing with you about someone else then you need to understand that they are probably telling others about you. Assume that everything you say in their presence and everything you do is fair game for them to repeat. Think of them as a two way street.
So? Obviously we are not to be this way. Maybe not so obvious is that we should not “meddle” (associate NASB) (6148) with such people.