The ESV, like many English versions, reckons that the prophecy regarding the Cushites is a future-oriented prophecy. It is possible, however, that the Hebrew could refer to a past event; more literally, it reads, “Also you, O Cushites—slain of my sword are they!” Such could be a reference to Assyria’s destruction of the twenty-fifth (Cushite) dynasty of Egypt in 663 BC, which happened roughly a generation before Zephaniah’s ministry (Isaiah 20:1–6).1
12 You also, O Cushites, shall be slain by my sword.