9. in a moment—It should not decay slowly, but be suddenly and unexpectedly destroyed; in a single night it was taken by Cyrus. The prophecy was again literally fulfilled when Babylon revolted against Darius; and, in order to hold out to the last, each man chose one woman of his family, and strangled the rest, to save provisions. Darius impaled three thousand of the revolters.
in … perfection—that is, "in full measure."
for … for—rather, "notwithstanding the … notwithstanding"; "in spite of" [Lowth]. So "for" (Nu 14:11). Babylon was famous for "expiations or sacrifices, and other incantations, whereby they tried to avert evil and obtain good" [Diodorus Siculus].