Charles Ellicott Commentary Ezekiel 21:5

"and all flesh shall know that I, Jehovah, have drawn forth my sword out of its sheath; it shall not return any more." — Ezekiel 21:5 (ASV)

It shall not return any more — that is, until it has fully accomplished its purpose. Other judgments upon Israel had been arrested in mercy—the sword had been returned to the scabbard while its work was still incomplete. This will go on to the end.