36:9
وَجَعَلْنَا مِنۢ بَيْنِ أَيْدِيهِمْ سَدًّا وَمِنْ خَلْفِهِمْ سَدًّا فَأَغْشَيْنَـٰهُمْ فَهُمْ لَا يُبْصِرُونَ
And We have put before them a barrier and behind them a barrier and covered them, so they do not see.
Ya-Sin
وَجَعَلْنَا مِنۢ بَيْنِ أَيْدِيهِمْ سَدًّا وَمِنْ خَلْفِهِمْ سَدًّا فَأَغْشَيْنَـٰهُمْ فَهُمْ لَا يُبْصِرُونَ
And We have put before them a barrier and behind them a barrier and covered them, so they do not see.
Nearby ayahs help place verse 36:9 in sequence and meaning.
لَقَدْ حَقَّ ٱلْقَوْلُ عَلَىٰٓ أَكْثَرِهِمْ فَهُمْ لَا يُؤْمِنُونَ
Already the word has come into effect upon most of them, so they do not believe.
إِنَّا جَعَلْنَا فِىٓ أَعْنَـٰقِهِمْ أَغْلَـٰلًا فَهِىَ إِلَى ٱلْأَذْقَانِ فَهُم مُّقْمَحُونَ
Indeed, We have put shackles on their necks, and they are to their chins, so they are with heads [kept] aloft.
وَسَوَآءٌ عَلَيْهِمْ ءَأَنذَرْتَهُمْ أَمْ لَمْ تُنذِرْهُمْ لَا يُؤْمِنُونَ
And it is all the same for them whether you warn them or do not warn them - they will not believe.
إِنَّمَا تُنذِرُ مَنِ ٱتَّبَعَ ٱلذِّكْرَ وَخَشِىَ ٱلرَّحْمَـٰنَ بِٱلْغَيْبِ ۖ فَبَشِّرْهُ بِمَغْفِرَةٍ وَأَجْرٍ كَرِيمٍ
You can only warn one who follows the message and fears the Most Merciful unseen. So give him good tidings of forgiveness and noble reward.