The verse is in a letter from Jeremiah to the exiles in Babylon. Why would his letter to the exiles be directly applicable to Christians living in 2016? Here is the full text of the letter:
And these are the words of the letter which Jeremiah, the prophet, sent from Jerusalem to the remnant of the elders of the transmigration, and to the priests, and to the prophets, and to all the people, whom Nebuchadnezzar had led away from Jerusalem to Babylon, after king Jeconiah, with the queen, and the eunuchs, and the leaders of Judah and of Jerusalem, and the craftsmen and engravers, had departed from Jerusalem. It was sent by the hand of Elasah, the son of Shaphan, and by Gemariah, the son of Hilkiah, whom Zedekiah, the king of Judah, sent to Babylon to Nebuchadnezzar, the king of Babylon, saying: "Thus says the Lord of hosts, the God of Israel, to all who have been taken away, whom I have caused to be transferred from Jerusalem to Babylon: Build houses and live in them. And plant gardens, and eat from their fruit. Take wives, and conceive sons and daughters. And give wives to your sons, and give your daughters to husbands, and let them bear sons and daughters. And be multiplied there, and do not choose to be few in number. And seek the peace of the city, to which I have caused you to be taken away, and pray to the Lord on its behalf. For your peace will be in its peace. For thus says the Lord of hosts, the God of Israel: Do not allow your prophets and your diviners, who are in your midst, to seduce you. And you should pay no attention to your dreams, which you are dreaming. For they prophesy falsely to you in my name, and I have not sent them, says the Lord.
For thus says the Lord: When the seventy years will begin to be completed in Babylon, I will visit you. And I will raise up over you my good word, so that I may lead you back to this place. For I know the thoughts that I think over you, says the Lord: thoughts of peace and not of affliction, so that I may give you patience and an end. And you shall call upon me, and you shall go forth. And you shall pray to me, and I will heed you. You shall seek me. And you will find me, when you have sought me with your whole heart. And I will be found by you, says the Lord. And I will lead you back from your captivity. And I will gather you from all the nations and all the places, to which I have expelled you, says the Lord. And I will return you from the place to which I sent you into captivity. For you have said: "The Lord has raised up prophets for us in Babylon." For thus says the Lord, to the king who sits upon the throne of David, and to all the people who live in this city, to your brothers who have not departed with you in the transmigration: Thus says the Lord of hosts: Behold, I will send among them the sword, and famine, and pestilence. And I will make them like the bad figs, which cannot be eaten, because they are very bad. And I will pursue them with the sword, and with famine, and with pestilence. And I will give them over to affliction, amid all the kingdoms of the earth: as a curse, and in stupor, and with hissing, and as a disgrace among all the nations to which I have driven them out. For they have not listened to my words, says the Lord, which I sent to them through my servants, the prophets, rising while it was still night, and sending. But you have not listened, says the Lord. Therefore, listen to the word of the Lord, all you of the transmigration, whom I have sent away from Jerusalem into Babylon. Thus says the Lord of hosts, the God of Israel, to Ahab, the son of Kolaiah, and to Zedekiah, the son of Maaseiah, who prophesy falsely to you in my name: Behold, I will deliver them into the hands of Nebuchadnezzar, the king of Babylon, and he will strike them down before your eyes. And a curse will be taken up about them, by all the captives of Judah that are in Babylon, saying: "May the Lord make you like Zedekiah, and like Ahab, whom the king of Babylon fried in the fire!" For they have acted foolishly in Israel, and they have committed adultery with the wives of their friends, and they have spoken lying words in my name, which I did not command them. I am the Judge and the Witness, says the Lord. Jeremiah 29:1-23
I underlined the verse to which George referred.