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 people its void places, and especially the Israelites. They have dwelt there long enough to feel pity for her, when they contrast her past magnificence with her terrible fall. Compare Jeremiah 29:7.