John Calvin on Jeremiah 50:18

What I have said may hence with more certainty be inferred — that the similitude which God employed was intended for this end, that having assumed the person of one in sorrow, he might represent as it were to their eyes his sympathy, he then shows that he would be the avenger of the cruelty which the Chaldeans had practiced, as he had already been the avenger of all the evils which the Assyrians had done to his people.

We must bear in mind the time — for the meaning of this passage depends on history. The Assyrians were stronger than the Chaldeans when they harassed the kingdom of Israel: for we know that in the time of Hezekiah the king of Babylon sent to him to seek his favor, and to allure him to a confederacy. While then the monarchy of Assyria was formidable, the Assyrians were very hostile to the Israelites and also to the Jews: what followed? Nineveh was overthrown, and Babylon succeeded in its place; and so they who had ruled were constrained to bear the yoke, and thus Babylon made the Assyrians captive to itself. God now refers to this judgment, which was known to all. The Assyrians themselves did not indeed think that the God of Israel was the avenger of his people, but yet it was so. Hence God here declares that he had already given a manifest proof of the solicitude which he had for the welfare of his people: as then he had punished Assyria, so he declares that he would take vengeance on the Babylonians. And thus, by an example, he confirms what might have appeared incredible. For who could have thought that that monarchy could so suddenly fall? And yet it happened beyond what any could have anticipated. God here repeats what had taken place, that the faithful might feel assured that the judgment which the Assyrians had experienced, awaited the Babylonians. This is the plain meaning of the Prophet. It follows, —

Jeremiah 50:19

19. And I will bring Israel again to his habitation, and he shall feed on Carmel and Bashan, and his soul shall be satisfied upon mount Ephraim and Gilead.

19. Et reducam Israelem ad caulas suas, et pascetur in (monte) Carmel et Basan, et in monte Ephraim et Gilead; satiabitur anima ejus.