Jeremiah warned against those who delivered messages that went against the Lord's:
[False] prophets made predictions that supported idol worship
diviners claimed to predict the future by reading the stars, looking into crystal balls, and analyzing animal livers
Interpreters of dreams predicted the future by explaining people's dreams
Mediums claimed to talk to dead people
Sorcerers cast spells to harm or bless people by saying certain words or phrases
You will not serve the king of Babylon: This prediction was incorrect. Nebuchadnezzar conquered the entire region starting in 605 BC.