Albert Barnes Commentary Jeremiah 25:9

"behold, I will send and take all the families of the north, saith Jehovah, and [I will send] unto Nebuchadrezzar the king of Babylon, my servant, and will bring them against this land, and against the inhabitants thereof, and against all these nations round about; and I will utterly destroy them, and make them an astonishment, and a hissing, and perpetual desolations." — Jeremiah 25:9 (ASV)

The term families is probably used here to signify the widespread empire of Nebuchadnezzar.

My servant — This title, so remarkable in the Old Testament as the special epithet, first of Moses, and then of the Messiah, is three times given to Nebuchadnezzar, and marks the greatness of the commission entrusted to him.