Albert Barnes Commentary Jeremiah 16:21

"Therefore, behold, I will cause them to know, this once will I cause them to know my hand and my might; and they shall know that my name is Jehovah." — Jeremiah 16:21 (ASV)

This once - Whether we consider the greatness of the national disgrace and suffering caused by it, or its effect upon the mind of the Jews, the burning of Jerusalem by Nebuchadnezzar, followed by the captivity of the people at Babylon, stands out as the greatest manifestation of God’s “hand” in all His dealings with them.