Jamieson, Fausset and Brown on Jeremiah 40:10

10. Mizpah--lying on the way between Babylon and Judah, and so convenient for transacting business between the two countries.

As for me ... but ye--He artfully, in order to conciliate them, represents the burden of the service to the Chaldeans as falling on him, while they may freely gather their wine, fruits, and oil. He does not now add that these very fruits were to constitute the chief part of the tribute to be paid to Babylon: which, though fruitful in corn, was less productive of grapes, figs, and olives [Herodotus, 1.193]. The grant of "vineyards" to the "poor" (Jr 39:10) would give hope to the discontended of enjoying the best fruits (Jr 40:12).