Passage
And thou shalt speak to Shemaiah the Nehelamite, saying,
And thou shalt speak to Shemaiah the Nehelamite, saying,
Jeremiah 29:22 And of them shall be taken up a curse by all the captivity of Judah that are in Babylon, saying, Jehovah make thee like Zedekiah and like Ahab, whom the king of Babylon roasted in the fire;
Jeremiah 29:23 because they have committed infamy in Israel, and have committed adultery with their neighbours' wives, and have spoken words of falsehood in my name, which I had not commanded them: and I [am] he that knoweth, and [am] witness, saith Jehovah.
Jeremiah 29:24 And thou shalt speak to Shemaiah the Nehelamite, saying,
Jeremiah 29:25 Thus speaketh Jehovah of hosts, the God of Israel, saying, Because thou hast sent letters in thy name unto all the people that are at Jerusalem, and to Zephaniah the son of Maaseiah the priest, and to all the priests, saying,
Jeremiah 29:26 Jehovah hath made thee priest in the stead of Jehoiada the priest, that there should be officers [in] the house of Jehovah, over every madman and self-made prophet, that thou shouldest put him in the stocks and in the shackles.
The verse centers on "thou", "shalt", "speak", "shemaiah", "nehelamite", and "saying". It is saying that the verse draws attention to "thou" and "shalt", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 23's "because they have committed infamy in Israel..." into verse 25's "Thus speaketh Jehovah of hosts the God...", so "thou" and "shalt" belong inside that flow. In Jeremiah context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "thou" and "shalt" with trust shaped by these words, not by a vague optimism outside the passage.