Jeremiah 21:4 - Matthew Poole's English Annotations on the Holy Bible

The honour that the king of Judah had put upon the prophet, in sending these special messengers to him, is no temptation to this good prophet to prophesy smooth and pleasing things, for which he had no warrant from God. The prophet styleth God the God of Israel, because the whole posterity of Jacob were in covenant with God; notwithstanding which, ten parts of twelve were at this time carried into a captivity from which they never returned; yet God was the God of Israel, for all were not Israel that were descended from Israel, but those only who were Israelites indeed, without guile; so that the prophet by this name given to God doth both assert God's faithfulness to his covenant, and also show the consistency of that faithfulness with those judgments which he was now bringing upon that remnant of Israel which yet were in their own land. Tile message which God by the prophet sendeth to Zedekiah is exceeding terrible. The sum of it is, that as they had not dealt with God according to the works of Israel, and the former generation that descended from him, or those at least who were the true Israel of God; so they must not expect that God should deal with them according to his former wondrous works, but that as he with the pure had showed himself upright, so with the froward he should show himself froward. For God had determined to turn into their own bowels, and against themselves, the weapons they had in their hands taken up against the king of Babylon and the Chaldeans that were now besieging them (by which we may learn that this message was sent during the time of the siege, probably about the beginning of it, for it lasted eighteen months). I will assemble them into the midst of this city; God threateneth to bring the Chaldeans into the midst of the holy city, that their city should be broken up, their arms taken from them, and they killed with their own swords. There is a great emphasis in the pronoun I. It is not an enemy that is to be feared, but God's being our enemy.