Proverbs 20:19 "He that goeth about as a talebearer revealeth secrets: therefore meddle not with him that flattereth with his lips."
This person who Solomon describes here is one who gives lavish praise to one person that feeds their ego and lies are one and the same person. This person is dishonest. He slanders others to elevate the one he is flattering even higher, but then has no problem to then go betray them behind their back. He is two-faced. He gives allegiance in appearance to one and then to the other, while slandering the first in an attempt to elevate his own position or create scandal. H. A. Ironside says this about this two-faced individual, "He who flatters to the face will as readily scandalize behind the back. By soft, sinuous words and ways he will gain the confidence of his victim, appealing to his pride and love of approbation, and thus loosening his tongue, until he relates things far better left unsaid. When he has thus lured him on to baring his heart, he will go to others and pour into their ears what he has just learned, flattering them in the same way and giving them to suppose that they alone are the recipients of his favor."
Solomon urges his son to avoid the flatterer. The Amalekite who lied and said he killed King Saul, supposing that this would bring joy to the ears of David, was killed himself for slaying the Lord’s anointed (2 Samuel 1:1-16). This Amalekite lied about how King Saul died and tried to flatter himself and David through his lie, but it did not work. It ended up in his demise. Romans 16:18 describes these type of people that stir up scandal as those that serve not our Lord Jesus Christ, but their own belly. However, they are able to deceive the simple through their flattering speech and good words.
Now let’s draw some applications. Do I love the praise of others? Do I enjoy when people flatter me or do I reject it? Do I recognize the trap of those who flatter people? Am I honest with others or do I give others praise in order to gain an advantage over them? Do I meddle (mingle) with those who are gossips and flatterers? Am I serving Christ, or myself?