John Gill 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)

If you will still abide in this land In the land of Judea, their native country, where they had always lived, and where they continued when their brethren were carried captive; and yet they thought of going out of it, which the Lord knew; and therefore to encourage them to abide in it, and not think of departing into Egypt;

that if they would take up their residence in it, and determine to continue there, he thus promises them: then will I build you, and not pull [you] down: and I will plant you , and not pluck [you] up ;

that is, they should be firm and stable, happy and prosperous; and abound with all kind of blessings, and increase in numbers, wealth, and riches. The metaphors are taken from building houses, and planting fields and vineyards:

for I repent me of the evil that I have done unto you ; not that he had done any unjust thing to them; or that he changed his mind concerning them; but that he had compassion on them, and would change his way and course of providence towards them, according to his unchangeable will.