To CALL DOWN A CURSE — to place something under a katathema, an anathema, a thing devoted to destruction. ⚠ It is not swearing in the sense of foul language, which is how KJV's 'began to curse and to swear' (Matthew 26:74) has been read for centuries; it is the formal invocation of a curse on oneself as a guarantee of truthfulness — may this happen to me if I am lying. That is why it is the THIRD step of Peter's denials and not merely a louder version of the first: he denies plainly (v70), then denies under oath (v72), then calls down curses (v74). Denial, perjury, self-imprecation. The word is used only here in the New Testament. ⚠ Its NOUN, katathema, is used only once as well — at Revelation 22:3, the last chapter of the Bible: 'and there will no longer be any curse.' The only two appearances of this root in the New Testament are the worst moment of Peter's life and the abolition of the thing he called down. Neither text knows about the other; a concordance does. → first discussed at Matt 26:74