1 Samuel 12:21 - Ellicott's Commentary On The Whole Bible

For then should ye go after vain things. — The passage is more forcible without the “for” and the words in italics supplied in the English translation. The verse without it would run thus: “Turn ye not aside after vain things which cannot profit,” &c. Singularly enough, not one of the ancient versions translate the Hebrew ki, “for”: they all omit it. It is therefore clear that this “for” has, through some copyist’s error, got into the text since the versions were made.