"And if you deny, then nations before you have already denied." That is: Allah destroyed them. He warns them that what befell those (previous nations) might befall them if they do not believe. "And the duty of the Messenger is only clear notification." That is: It is not incumbent upon you to force people to believe.
Surat Al-Qasas from (verse 19 to verse 23).
﴿وَإِنْ تُكَذِّبُوا فَقَدْ كَذَّبَ أُمَمٌ من قبلكُمْ﴾ أَيْ: فَأَهْلَكَهُمُ اللَّهُ، يُحَذِّرُهُمْ أَنْ يَنْزِلَ بِهِمْ مَا نَزَلَ بِهِمْ إِنْ لَمْ يُؤْمِنُوا ﴿وَمَا عَلَى الرَّسُول إِلَّا الْبَلَاغ الْمُبين﴾ أَيْ: لَيْسَ عَلَيْكَ أَنْ تُكْرِهَ النَّاس على الْإِيمَان.
سُورَة الْقَصَص من (آيَة ١٩ آيَة ٢٣).
