31:27-34 The people of God shall become numerous and prosperous. In Heb 8:8,9, this place is quoted as the sum of the covenant of grace made with believers in Jesus Christ. Not, I will give them a new law; for Christ came not to destroy the law, but to fulfil it; but the law shall be written in their hearts by the finger of the Spirit, as formerly written in the tables of stone. The Lord will, by his grace, make his people willing people in the day of his power. All shall know the Lord; all shall be welcome to the knowledge of God, and shall have the means of that knowledge. There shall be an outpouring of the Holy Spirit, at the time the gospel is published. No man shall finally perish, but for his own sins; none, who is willing to accept of Christ's salvation.
31. the days … new covenant with … Israel … Judah—The new covenant is made with literal Israel and Judah, not with the spiritual Israel, that is, believers, except secondarily, and as grafted on the stock of Israel (Ro 11:16-27). For the whole subject of the thirtieth and thirty-first chapters is the restoration of the Hebrews (Jer 30:4, 7, 10, 18; 31:7, 10, 11, 23, 24, 27, 36). With the "remnant according to the election of grace" in Israel, the new covenant has already taken effect. But with regard to the whole nation, its realization is reserved for the last days, to which Paul refers this prophecy in an abridged form (Ro 11:27).