not somebody's concern/none of somebody's concernPRIVATE/PERSONALif something is not your concern, you are not interested in it and you do not need to worry about it or become involved in it 某人不感兴趣的事;与某人无关的事 His affairs were none of her concern. 他的私事与她无关。
→ not somebody’s concern/none of somebody’s concern at concern1(2)