Jeremiah - Chapter 29
False Prophets Called to Task
Jeremiah sent a scroll to the elders who were exiled with Yehoyachin, as well as the priests, prophets and people who were already exiled to Babylonia. The scroll said that they might as well get comfortable in exile: build houses, plant gardens, get married and have families. They should seek the peace of their new cities, because they're going to be staying there; the peace of the city will be their peace. They should not let false prophets mislead them and if they have a dream to the contrary, it's just a dream. There will be 70 years of Babylonian exile, at the end of which G-d will bring them back.
G-d exiled them for their ultimate peace, to give them a future. The Jewish people will eventually turn to G-d and He will answer them. They will seek G-d and find Him, and He will return the exiles from all the nations. Don't believe false "prophets" who claim to represent G-d in exile. G-d has said regarding King Tzidkiyahu (who was not exiled) and the people remaining in Jerusalem that there would be war, famine and plague. They would be like the inedible figs (in chapter 24) and would serve as an example to the nations of the world. G-d sent them prophets to warn them, but the people ignored His messengers.
G-d spoke regarding two false prophets named Ahab the son of Kolayah and Tzidkiyahu the son of Ma'aseya. They will fall into the hands of Nebuchadnezzar, who will kill them. They will become a curse among the people, "May you be like Ahab and Tzidkiyahu, whom Nebuchadnezzar burned to death." Why were these two false prophets singled out for such a punishment? They not only spoke falsely in G-d's name, they committed adultery with other men's wives. (The Talmud in Sanhedrin 93a says that they used their position as "prophets" to convince those women that G-d wanted them to be unfaithful with them.)
G-d also spoke regarding Shemayahu the Nechelami. He pretended to be a prophet and sent letters to the people in Jerusalem and the kohanim (priests), saying that G-d appointed a Kohein named Tzefania to be the High Priest in place of Yehoyada. Shemayahu said that Tzefania and some other priests were officers over madmen and self-proclaimed prophets, with the authority to imprison them. Since that is the case (Shemayahu said), why hasn't Tzefania stopped Jeremiah? The exile is essentially Jeremiah's fault (Shemayahu said), since he told everyone to get comfortable because it's going to be a long stay!
Tzefania read this letter to Jeremiah and G-d told him to relate to the people in exile that Shemayahu was a false prophet, not sent by Him. Therefore, none of Shemayahu's descendants will ever hold any office of power or influence. Furthermore, Shemayahu himself will not witness the redemption.