1) Jeremiah was called by God to preach a message warning of coming judgment but forbidden from marrying or having children as his life would serve as a living illustration.
2) Hananiah contradicted Jeremiah's message, claiming Babylon would be defeated within two years and vessels taken from the temple returned, using similar words to Jeremiah but with a contradictory message.
3) God confirmed Jeremiah's message was true through Hananiah dying within months, proving Jeremiah spoke for God while Hananiah misled the people, teaching rebellion against God.