Charles Ellicott Commentary Jeremiah 51:38

"They shall roar together like young lions; they shall growl as lions` whelps." — Jeremiah 51:38 (ASV)

They shall roar together like lions ... —The words are not a continuation of the picture of the preceding verse, but carry us to the scene of revelry that preceded the capture of the city. The princes of Babylon were as young lions (Amos 3:4) roaring over their prey. The first clause as well as the second conveys this meaning, and there is probably a reference to the youth of rulers like Belshazzar.