Jeremiah 9:2-6, 8

If only I had a traveler’s lodging place in the wilderness,  I would abandon my people and depart from them, for they are all adulterers,  a solemn assembly of treacherous people.  They bent their tongues like their bows; lies and not faithfulness prevail in the land, for they proceed from one evil to another, and they do not take me into account.  This is the  LORD’s declaration. Everyone has to be on guard against his friend. Don’t trust any brother, for every brother will certainly deceive,  and every friend spread slander.  Each one betrays his friend;  no one tells the truth. They have taught their tongues to speak lies; they wear themselves out doing wrong. You live in a world of deception.  , In their deception they refuse to know me.  This is the  LORD’s declaration.

Their tongues are deadly arrows — they speak deception.  With his mouth one speaks peaceably with his friend, but inwardly he sets up an ambush.