cut off your nose to spite your face
cut off your nose to spite your faceor
cut your nose off to spite your face
If someone cuts off their nose to spite their face, or cuts their nose off to spite their face, they do something to punish someone but in doing so harm themselves more than they harm the person they are punishing. The manager would probably like to leave Keane out of the squad but he knows that he'd be cutting his nose off to spite his face in losing a genuinely world-class player. Note: In this expression, `to spite' means to deliberately annoy or upset.
cut off your nose to spite your facedisadvantage yourself in the course of trying to disadvantage another.
This idea was proverbial for self-defeating malice in both medieval Latin and medieval French, and has been found in English since the mid 16th century.