Adam Clarke on Jeremiah 21:1

The word which came unto Jeremiah - The chapters in the remaining parts of this prophecy seem strangely interchanged. This subject has been mentioned in the introduction, and some tables given; and to these the critical reader is requested to refer. The discourse here was delivered about the ninth year or the reign of Zedekiah. This chapter, observes Dr. Blayney, contains the first of those prophecies which were delivered by Jeremiah, subsequent to the revolt of Zedekiah, and the breaking out of the war thereupon; and which are continued on to the taking of Jerusalem, related in chap. 29, in the following order: Jer 21:1-14, 34, 37, 32, 33, 38, 39.

Pashur the son of Melchiah - There can be little doubt that this Pashur was a different person from him who was called the son of Immur in the preceding chapter.