Do you not see that Allah drives along the clouds, then gathers them together, then piles them up, so that you see the rain coming forth from their midst? And He sends down of the clouds that are (like) mountains wherein is hail, afflicting therewith whom He pleases and turning it away from whom He pleases; the flash of His lightning almost takes away the sight.

And if they should see a portion of the heaven coming down, they would say: Piled up clouds.