ˊㄈㄥfēngㄅㄨˋㄑㄧˇㄌㄤˋlàng

无风不起浪
  1. 刮風不起波浪比喻事出有因 無風不起浪群情沸騰總是事出有因」。

lit. without wind there cannot be waves (idiom)​; there must be a reason, no smoke without fire