John Gill Commentary Jeremiah 29:15

"Because ye have said, Jehovah hath raised us up prophets in Babylon;" — Jeremiah 29:15 (ASV)

Because you have said That is, some of them; for here the Lord, by the prophet, turns from the godly among the captives, whom he had been advising, encouraging, and comforting before, to those who gave heed to the false prophets, who promised them a speedy return to their own land, and which they believed; and therefore rejected and despised the prophecies of Jeremiah, and others.

The Lord has raised us up prophets in Babylon; and therefore needed no other prophets that were in Judea, or in Jerusalem, nor should listen to them; but believe those that were raised up among themselves, rather than others at a distance; and though these were false prophets, yet, since they prophesied to them things that were agreeable, they were willing to believe them, and to consider and receive them as prophets sent by God, even though they were not.