Jeremiah sees a potter whose clay has not turned out the way he wanted to, and God uses this to explain his actions. God will rework Israel into a different type of vessel if Israel will change its path, which Paul would echo in 2 Timothy 2:20-21. This does not match what the priests and false prophets were saying at the time, but those people, both then and now are not guaranteed to proclaim what is in the Bible and the catechism. Jeremiah shatters a flask to emphasize the analogy.
Jeremiah is placed in stocks by Pashur son of Immer, and the people seek to kill Jeremiah, for prophesying things like Israel will be captured, but people will die unless they surrender. Even Jeremiah’s own family is against him, and Jeremiah is despairing more than at any other point in the Bible.
At this point, the timeline is interrupted and goes back to the reign of Josiah.