ㄗㄨㄛˋㄕㄢzuòshānㄍㄨㄢguānㄏㄨˇㄉㄡˋhǔdòu

坐山观虎斗
  1. 觀看老虎爭鬥比喻袖手旁觀介入別人鬥爭伺機從中得利 坐山觀虎鬥不但毫髮無傷坐享其成」。

sit on the mountain and watch the tigers fight, watch in safety whilst others fight then reap the rewards when both sides are exhausted (idiom)​