Charles Ellicott Commentary Zephaniah 2:1

"Gather yourselves together, yea, gather together, O nation that hath no shame;" — Zephaniah 2:1 (ASV)

Gather yourselves together. — This rendering has little to recommend it. Two translations of the obscure verb used here are possible: Sift yourselves, indeed sift — that is, winnow out the sins that have roused Jehovah’s anger; or Bend yourselves, indeed bend. We prefer the latter. The contumacious nation is exhorted to bend in submission to Jehovah before His judgment is revealed.

O nation not desired. — Better, O nation that are not abashed — namely, by God’s threats: the shameless defiant nation; so the Septuagint, ἔθνος.