Isaiah 13:4b–Isaiah 13:8 describes the death of the Babylonian king, and the future oppression the people would face under this king. At the time of this prophecy, the people of Judah did not experience much oppression by the Babylonians yet; the Assyrians were the big oppressors at that time. They would be freed of this oppression by the death of the Babylonian king.
4 you will take up this taunt against the king of Babylon: “How the oppressor has ceased, the insolent fury ceased!