Surah An Naml Tafseer

وَتَرَى الْجِبَالَ تَحْسَبُهَا جَامِدَةً وَهِيَ تَمُرُّ مَرَّ السَّحَابِ

And you will see the mountains and think them solid, but they shall pass away as the passing away of the clouds.

meaning, you will see them as if they are fixed and as if they will remain as they are, but they will pass away as the passing away of the clouds, i.e., they will move away from their places.

This is like the Ayat:

يَوْمَ تَمُورُ السَّمَأءُ مَوْراً

وَتَسِيرُ الْجِبَالُ سَيْراً

On the Day when the heaven will shake with a dreadful shaking, And the mountains will move away with a (horrible) movement. (52:9-10)

وَيَسْـَلُونَكَ عَنِ الْجِبَالِ فَقُلْ يَنسِفُهَا رَبِّى نَسْفاً فَيَذَرُهَا قَاعاً صَفْصَفاً

لااَّ تَرَى فِيهَا عِوَجاً وَلاا أَمْتاً

And they ask you concerning the mountains:say, "My Lord will blast them and scatter them as particles of dust. Then He shall leave them as a level smooth plain. You will see therein nothing crooked or curved." (20:105-107)

وَيَوْمَ نُسَيِّرُ الْجِبَالَ وَتَرَى الاٌّرْضَ بَارِزَةً

And (remember) the Day We shall cause the mountains to pass away, and you will see the earth as a leveled plain. (18:47)

صُنْعَ اللَّهِ الَّذِي أَتْقَنَ كُلَّ شَيْءٍ

The work of Allah, Who perfected all things,

means, He does that by His great power.

..

الَّذِي أَتْقَنَ كُلَّ شَيْءٍ

Who perfected all things,

means, He has perfected all that He has created, and has fashioned it according to His wisdom.

إِنَّهُ خَبِيرٌ بِمَا تَفْعَلُونَ

verily, He is well-acquainted with what you do.

means, He knows all that His servants do, good or evil, and He will reward or punish them accordingly.

Then Allah describes the state of the blessed and the doomed on that Day, and says