Circumcise yourselves to the LORD, remove the foreskin of your hearts.... -Jeremiah 4:4a
Sounds a lot like Paul, doesn't it? Here's just one other example of how the prophets can shed light on the New Testament, in this case, Jesus specifically. During Jesus' last journey to Jerusalem, he sees a fig tree with no fruit. He's so upset that he curses the tree, which then withers and dies. Well...that seems a bit drastic doesn't? If farmers killed their crops every time the yield wasn't what they wanted, well, we'd all starve. Why does Jesus do that? Is it really about the tree? Not if we know Jeremiah.
When I wanted to gather them, says the LORD, there are no grapes on the vine, nor figs on the fig tree; even the leaves are withered, and what I gave them has passed away from them. -Jeremiah 8:13
Jeremiah's prophecy is about Jerusalem and Judah, and how they had squandered every gift God had given them. God had planted them to be a blessing, to bear fruit for others to enjoy. Instead they were shriveled, useless crops. So, in Jeremiah, God would send them into exile. He would bring the way they were to an end and start over.
On his way to Jerusalem, Jesus re-contextualizes this oracle, but instead of pre-exilic Jerusalem, it is Jesus' own Jerusalem that is fruitless. It is good for nothing. And Jesus, now playing the part of God returning to his city, pronounces a new oracle of judgment upon a city that has abandoned his ways. Jerusalem, and the corruption, superficial religion, and selfishness it represented, would end up just like the tree. Roughly forty years later it does just that when the Roman army flattens it. God would build a new people in the followers of his son, just like 500 years before he had rebuilt his people in the returned exiles.
Stopping point: Jeremiah 22