空穴來風未必無因 [－－来风－－无－]

Jyutping hung1 jyut6 loi4 fung1 mei6 bit1 mou4 jan1
Pinyin kòng xué lái fēng wèi bì wú yīn

Definitions (CC-CEDICT)
  1. wind does not come from an empty cave without reason
  2. there's no smoke without fire (idiom)