1. He assures them that he wrote in the name of the Lord of hosts, the God of Israel, who indited the letter; Jeremiah was but the scribe or amanuensis. It would be comfortable to them, in their captivity, to hear that God is the Lord of hosts, of all hosts, and is therefore able to help and deliver them; and that he is the God of Israel still, a God in covenant with his people, though he contend with them, and their enemies for the present are too hard for them. This would likewise be an admonition to them to stand upon their guard against all temptations to the idolatry of Babylon, because the God of Israel, the God whom they served, is Lord of hosts. God's sending to them in this letter might be an encouragement to them in their captivity, as it was an evidence that he had not cast them off, had not abandoned them and disinherited them, though he was displeased with them and corrected them; for, if the Lord had been pleased to kill them, he would not have written to them.