﴿ لَهُم مِّن فَوْقِهِمْ ظُلَلٌۭ مِّنَ ٱلنَّارِ وَمِن تَحْتِهِمْ ظُلَلٌۭ ۚ ذَٰلِكَ يُخَوِّفُ ٱللَّهُ بِهِۦ عِبَادَهُۥ ۚ يَٰعِبَادِ فَٱتَّقُونِ ﴾

“Clouds of fire will they have above them, and [similar] clouds beneath them…” In this way does God imbue His servants with fear. O you servants of Mine! Be, then, conscious of Me -”

Above them they will have canopies layers of fire and beneath them they will have similar canopies of fire. That is what God frightens His servants with that is the believing ones that they may have fear of Him — this sense of the verse is suggested by what follows “So O servants of Mine fear Me!”’