none of business
none of (one's) business
Something that is of no concern to another. It's really none of his business what I do with the money I earn.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
none of someone's business
not of someone's concern. (A gentle rebuke.) Q: When are you going to leave for home? A: None of your business. How I managed to afford all this is none of your business.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.