Charles Ellicott Commentary Jeremiah 39:11

"Now Nebuchadrezzar king of Babylon gave charge concerning Jeremiah to Nebuzaradan the captain of the guard, saying," — Jeremiah 39:11 (ASV)

Nebuchadrezzar king of Babylon... — It is clear that Nebuchadrezzar had been well informed of the part Jeremiah had taken from first to last in counselling submission. He may have heard this from the deserters named in Jeremiah 39:9, or even from the lips of Zedekiah. Possibly the journey to Euphrates, which we read about in Jeremiah 13:5, may, even at an earlier period, have brought the king and the prophet into contact.

From the time of Nebuzar-adan’s arrival, Jeremiah's position obviously changed for the better, and he became an honoured and trusted counsellor. It appears from Jeremiah 40:1 that the prophet had at first been taken in chains to Ramah with the other captives. Probably he had been sent back to Jerusalem when the others were carried off to Riblah or Babylon (Jeremiah 39:6–9).