وَإِن يَرَوْا كِسْفًا مِّنَ السَّمَاء سَاقِطًا يَقُولُوا سَحَابٌ مَّرْكُومٌ
[52:44]
And if they should see a portion of the heaven coming down, they would say: Piled up clouds.
Were they to see a piece of the sky falling (on them), they would (only) say: "Clouds gathered in heaps!"
And if they were to see a fragment of the heaven falling, they would say: A heap of clouds.