The Lord said: "You Be as Bronze"

 Jeremiah 15:19 Therefore thus says the Lord:
“If you return, I will restore you, and you shall stand before me.
If you utter what is precious, and not what is worthless,
    you shall be as my mouth.
They shall turn to you, but you shall not turn to them.
20 And I will make you to this people a fortified wall of bronze;
they will fight against you, but they shall not prevail over you,
for I am with you to save you and deliver you, declares the Lord.
21 I will deliver you out of the hand of the wicked,
    and redeem you from the grasp of the ruthless.”

After being used by God to pronounce judgment without relent, Jeremiah received a lot of grief. So much in fact, that in the paragraph preceding this one he laid out a complaint to God.  He, and a small remnant, had remained faithful, but no one was listening, and he was getting the brunt of it.  God reminds Jeremiah of who he is: His mouthpiece, and that eventually those who resisted his words would eventually come to him for advice. Through it all God would protect him; he would not be exiled; God would make him strong and he would survive all the judgments to come. Bronze is strong and does not rust.