Surah Ya-Sin 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.

Translation: Saheeh International

Tafsir

And We have set before them a barrier read saddan or suddan in both instances and behind them a barrier; so We have covered them so they do not see — this is also figurative depicting the way in which the paths of faith are closed to them.

Excerpt from Tafsir al-Jalalayn, commentary on 36:9, via Quran.com. The reader has the full commentary and 9 more tafsirs.