Jeremiah 9:3-5, 8

They bend their tongue like a bow; falsehood and not truth has grown strong in the land; for they proceed from evil to evil, and they do not know me, declares the LORD. Let everyone beware of his neighbor, and put no trust in any brother, for every brother is a deceiver, and every neighbor goes about as a slanderer. Everyone deceives his neighbor, and no one speaks the truth; they have taught their tongue to speak lies; they weary themselves committing iniquity.

Their tongue is a deadly arrow; it speaks deceitfully; with his mouth each speaks peace to his neighbor, but in his heart he plans an ambush for him.