John Gill Commentary Jeremiah 40:6

"Then went Jeremiah unto Gedaliah the son of Ahikam to Mizpah, and dwelt with him among the people that were left in the land." — Jeremiah 40:6 (ASV)

Then went Jeremiah to Gedaliah the son of Ahikam to Mizpah ,
&c.] A city in the tribe of Benjamin, not far from Ramathon; which, as Josephus says, was about five miles from Jerusalem. Jeremiah took the captain's advice, though it might have been better with him had he gone along with him to Babylon; but he chose rather to dwell in his own land, and suffer affliction with the people of God, than to dwell at ease in a foreign and idolatrous land: and dwelt with him among the people that were left in the land ;
among the poor people that Nebuzaradan left, who dwelt either at Mizpah or at Anathoth, and lived as they did.