none of my concernA blunt, dismissive way to say that something is not one's concern or that one does not care. The subject is often understood from context, as in 俺の知ったことじゃない (none of my concern).
JA: 彼が会社を辞めようと、私の知ったことじゃない。
EN: Whether he quits the company or not is none of my concern.