Jeremia 3:18

In those days when Jerusalem is glorified by being made the throne of the Lord, Judah along with Israel will come out of the north into the land which the Lord gave to their fathers. As the destruction of Jerusalem and of the temple is foretold implicite in Jer 3:16, so here the expulsion of Judah into exile is assumed as having already taken place, and the return not of Israel, only, but of Judah too is announced, as in Hos 2:2, and more fully in Eze 27:16. We should note the arrangement, the house of Judah with (על, prop. on) the house of Israel; this is as much as to say that Israel is the first to resolve on a return and to arise, and that Judah joins itself to the house of Israel. Judah is thus subordinated to the house of Israel, because the prophet is here seeking chiefly to announce the return of Israel to the Lord. It can surely not be necessary to say that, as regards the fulfilment, we are not entitled hence to infer that the remnant of the ten tribes will positively be converted to the Lord and redeemed out of exile sooner than the remnant of Judah. For more on this point see on Jer 31:8.

The foregoing chapter was wholly taken up with reproofs and threatenings against the people of God, for their apostasies from him; but in this chapter gracious invitations and encouragements are given them to return and repent, notwithstanding the multitude and greatness of their provocations, which are here specified, to magnify the mercy of God, and to show that as sin abounded grace did much more abound. Here, I. It is further shown how bad they had been and how well they deserved to be quite abandoned, and yet how ready God was to receive them into his favour upon their repentance (Jer 3:1-5) II. The impenitence of Judah, and their persisting in sin, are aggravated from the judgments of God upon Israel, which they should have taken warning by (Jer 3:6-11). III. Great encouragements are given to these backsliders to return and repent, and promises made of great mercy which God had in store for them, and which he would prepare them for by bringing them home to himself (Jer 3:12-19). IV. The charge renewed against them for their apostasy from God, and the invitation repeated to return and repent, to which are here added the words that are put in their mouth, which they should make use of in their return to God (Jer 3:20-25).

3:18 Judah and Israel would be among the people flowing to Jerusalem. The Lord would mercifully bring them from exile and once again settle them in the Promised Land (31:8; Isa 11:13; Ezek 37:16-22; Hos 1:11; Amos 9:15).