Charles Ellicott Commentary Jeremiah 32:39

"and I will give them one heart and one way, that they may fear me for ever, for the good of them, and of their children after them:" — Jeremiah 32:39 (ASV)

I will give them one heart, and one way— The previous verse has described the restoration of Israel in the old familiar all-inclusive terms—They shall be my people, and I will be their God (Exodus 6:7; Deuteronomy 14:2; Hosea 2:23). Here a new feature is added. The prophet, in his vision of the future, in place of the discords of the present—some serving Jehovah, and some Baal and Molech; some urging submission to Babylon, and some intriguing with Egypt—sees a unity in faith showing itself in unity of action.

The hope of Jeremiah has never yet been realized, but it has appeared as with a transfigured glory in the prayer of the Christ for His people that they all may be one, even as He and the Father are one (John 17:21–23), in the prayer of the Apostle, that all might be joined together in the unity of the faith (Ephesians 4:13). And that prayer also waits for its fulfillment, and receives only partial and (to use Bacon’s phrase) “germinant” accomplishments. “For ever” represents the Hebrew all the days.