And if you [people] deny [the message] - already nations before you have denied. And there is not upon the Messenger except [the duty of] clear notification.
English Transliteration
Wain tukaththiboo faqad kaththaba omamun min qablikum wama AAala alrrasooli illa albalaghu almubeenu
Tafsir of Verse 18
'But if you cry me lies, nations cried lies before you; and it is only for the Messenger to deliver the Manifest Message.'
"And if ye reject (the Message), so did generations before you: and the duty of the messenger is only to preach publicly (and clearly)."