He clings to his evil ways and refuses to repent — 怙恶不悛.
Tips
history
悛 is not used alone in modern Chinese; it survives almost only in 怙恶不悛 (to persist in evil without repenting), echoing the classical 长恶不悛. It joins the heart radical 忄 with 夋 for the sound.
register
Classical and bound — modern use is essentially the idiom 怙恶不悛.
