Jeremiah 42:12

And I will shew mercies unto you, that he may have mercy upon you, and cause you to return to your own land.

I will show mercies - rather, I will excite (in him) feelings of mercy toward you (Calvin).

That he may ... cause you to return - permit you to return to the peaceable enjoyment of the possessions from which you are wishing to withdraw through fear of the Chaldeans. By departing in disobedience they should incur the very evils they wished thereby to escape; and by staying they should gain the blessings which they feared to lose by doing so.