Jeremiah 28:14
For thus saith the LORD of hosts, the God of Israel; I have put a yoke of iron upon the neck of all these nations, that they may serve Nebuchadnezzar king of Babylon; and they shall serve him: and I have given him the beasts of the field also.
The word was given in the controversy between Jeremiah and the false prophets during the Babylonian captivity. Hananiah had broken the wooden yoke and promised freedom, quick release from Babylonian rule, and prosperity. In its place God Himself put a yoke of iron upon the neck of all these nations, including Judah and the surrounding nations, decreeing that they would serve Nebuchadnezzar king of Babylon and remain subject to him. He gave him the beasts of the field also, extending his authority over them with their beasts.
The iron yoke meant a severe, harsher bondage borne with full rigor, in place of the lighter wooden yoke they could have borne by submitting to the appointed period of Babylonian rule. If they had submitted, God would have restrained Nebuchadnezzar from taking lives and imposing galling, severe oppression. The warning thus confirmed Jeremiah's message of submission and exposed Hananiah's promise that the yoke would soon be broken as false and a lie. By resisting God's warning and plan and following false prophets, the people brought the harsher bondage upon themselves.
The testimony belongs among Jeremiah's writings about the captivity and the promised return that Daniel later studied to understand that Jerusalem's desolation would last seventy years. False reassurance that contradicted God's message strengthened the people to resist the true warning and made them more hostile toward the true prophet. God's declared judgment is not softened to suit those who prefer reassurance.