After Jeremiah had laid the grief of his people before the Lord (in verses 2–18), he now starts praying for salvation.
In the ancient Near East, when a land was conquered, it was thought that the god of that land was also dethroned (see 2 Chronicles 32:11–14). Jeremiah, however, rejects this view. He knows that the Lord of Israel reigns forever. Although his temple has been destroyed, his sovereign rule still stands. This is the basis on which Jeremiah and the faithful remnant now pleads with the Lord for salvation.
19 But you, O LORD, reign forever; your throne endures to all generations.