Adam Clarke on Jeremiah 25:1

The word that came to Jeremiah - to the fourth year - This prophecy, we see, was delivered in the fourth year of Jehoiakim, and the chapter that contains it is utterly out of its place. It should be between chapters 35 and 36.

The defeat of the Egyptians by Nebuchadnezzar at Carchemish, and the subsequent taking of Jerusalem, occurred in this year, viz., the fourth year of Jehoiakim.

The first year of Nebuchadrezzar - This king was associated with his father two years before the death of the latter. The Jews reckon his reign from this time, and this was the first of those two years; but the Chaldeans date the commencement of his reign two years later, viz., at the death of his father.