He is dancing with the devil - Idioms by The Free Dictionary
https://idioms.thefreedictionary.com/he+is+dancing+with+the+devil
WebTo associate or deal with a particularly malicious, immoral, or unscrupulous person or people. I know you think this guy can boost your career, but considering some of the stuff people say he's involved in, well, you're dancing with the devil if you ask me.
DA: 84 PA: 35 MOZ Rank: 39