空穴來風未必無因

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

Character by character

• 空(kòng)empty
• 穴(xué)cave
• 來(lái)come
• 風(fēng)wind
• 未(wèi)not yet
• 必(bì)certainly
• 無(wú)not to have
• 因(yīn)cause