«وَجَعَلْنَا مِنْ بَيْنِ أَيْدِيهِمْ سَدًّا وَمِنْ خَلْفِهِمْ سَدًّا فَأَغْشَيْنَاهُمْ فَهُمْ لَا يُبْصِرُونَ»
“We have placed a barrier before them and a barrier behind them, and covered them, so they do not see.” (Yā Sīn 36:9)
The image combines obstacles in both directions, enclosure and an inability to see. It powerfully conveys the state of people who cannot perceive or profit from the guidance before them.
The wording creates a complete scene, not merely an isolated image of a wall. Confining the statement to ordinary eyesight alone would overlook the moral setting in which resistance to truth is being discussed. The whole progression of the verse guides the intended understanding.