Why should he break the flask?
Malbim (1): It is normal to put honey in a Bakbuk. It has a narrow mouth; after the honey congeals, the only way to remove it is to break the Kli.
What is the significance of buying the flask and breaking it?
Malbim: This is a metaphor - Yisrael are full of bad counsel and thoughts of heresy. One cannot remove them via rebuke of Nevi'im. It is necessary to crush them without mercy to remove the evil counsel and end sin. First Yirmeyah descended to the potter and saw that while Yisrael are in Hashem's hands and Reshus, they are like clay in the potter's hand. If the Kli breaks, he fixes it and makes another Kli. Afilu Teima He showed him another parable. When Yisrael left Hashem's Reshus via idolatry, they are like a potter's Kli that was heated in the furnace and finished. Then, if it is broken, there is no solution.
