Jeremiah 28:8

The prophets that have been before me and before thee of old prophesied both against many countries, and against great kingdoms, of war, and of evil, and of pestilence.

Long before Jeremiah, true prophets had again and again lifted their voices against many countries and great kingdoms, foretelling war and disaster and pestilence to come upon nations. Jeremiah appealed to that unbroken history to show that his own warning of judgment was nothing new or strange, but stood fully in line with the established burden of the prophetic message. What had happened in the past had borne out those earlier warnings, for when the people refused to repent the threatened calamities had fallen as foretold. Against this stood the false prophet with his promise of prosperity, a message that emboldened the people to resist divine counsel and that sharpened their hostility toward Jeremiah himself.