Isaiah 8:8

and, he shall pass through Judah, penetrating to its remotest ends; he shall overflow and go over, he shall reach even to the neck, threatening Judah's very life; and the stretching out of his wings, as the streams leave the main channel of the river on either side, shall fill the breadth of thy land, O Immanuel, the people in whose midst the Messiah would be born. Thus the judgment would begin in Israel and progress southward to encompass Judah as well, threatening its existence. Therefore the end of the sentence is a call for help addressed to Immanuel, the Messiah, not to forsake His people, but to remember them in mercy.