Charles Ellicott Commentary Jeremiah 42:10

"If ye will still abide in this land, then will I build you, and not pull you down, and I will plant you, and not pluck you up; for I repent me of the evil that I have done unto you." — Jeremiah 42:10 (ASV)

Then will I build you, and not pull you down ... —We note the characteristic recurrence of the formulas with which Jeremiah’s work as a prophet had begun (Jeremiah 1:10). The word for “repent” does not imply regret for the past, as people repent of their sin, but, as in Jeremiah 18:8; Jeremiah 26:3, a change of purpose from what had been the intent of judgment to one of mercy. The prophet’s counsel is, as it had been all along, that the people should accept the punishment which God had inflicted on them, that they should stay where they were and as they were, and not in terror or suspicion seek safety in plans of their own devising.