Albert Barnes Commentary Jeremiah 51:8

"Babylon is suddenly fallen and destroyed: wail for her; take balm for her pain, if so be she may be healed." — Jeremiah 51:8 (ASV)

Destroyed - literally, broken, as was the hammer (Jeremiah 50:23). The cup, though of metal, is thrown down so violently as to be shattered by the fall.

Howl for her - The persons addressed are the many inhabitants of Babylon who were dragged from their homes to populate its empty places, and especially the Israelites. They have lived there long enough to feel pity for her, when they contrast her past magnificence with her terrible fall. Compare Jeremiah 29:7.