Jeremiah 32:39 - Ellicott's Commentary On The Whole Bible

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 realised, 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 fulfilment, and receives only partial and (to use Bacon’s phrase) “germinant” accomplishments. “For ever” represents the Hebrew all the days.