鹬蚌相争渔翁得利

the third party benefits from the tussle

yù bàng xiāng zhēng yú wēng dé lì ㄩˋ ㄅㄤˋ ㄒㄧㄤ ㄓㄥ ㄩˊ ㄨㄥ ㄉㄜˊ ㄌㄧˋ