The Terrors of the Day of Resurrection, and how the Wrongdoers will wish that They had taken a Path with the Messenger

Allah tells:

وَيَوْمَ تَشَقَّقُ السَّمَاء بِالْغَمَامِ وَنُزِّلَ الْمَلَائِكَةُ تَنزِيلًا ﴿٢٥﴾

And (remember) the Day when the heaven shall be rent asunder with clouds, and the angels will be sent down, with a grand descending.

Here Allah tells us about the terror of the Day of Resurrection and the tremendous events that will happen, including the splitting of heavens when they are pierced by the clouds, that is the shadow of the magnificent light which dazzles all sight.

The angels of heaven will come down on that Day and surround all creatures at the place of gathering, then the Lord, may He be blessed and exalted, will come to pass judgement.

Mujahid said,

This is as Allah says:

هَلْ يَنظُرُونَ إِلاَّ أَن يَأْتِيَهُمُ اللَّهُ فِي ظُلَلٍ مِّنَ الْغَمَامِ وَالْمَلَـئِكَةُ

Do they then wait for anything other than that Allah should come to them in the shadows of the clouds and the angels. (2:210)

الْمُلْكُ يَوْمَئِذٍ الْحَقُّ لِلرَّحْمَنِ ...

The sovereignty on that Day will be the true (sovereignty) of the Most Gracious,

This is like the Ayah,

لِّمَنِ الْمُلْكُ الْيَوْمَ لِلَّهِ الْوَحِدِ الْقَهَّارِ

Whose is the kingdom this Day: It is Allah's, the One, the Irresistible! (40:16)

In the Sahih it says:

أَنَّ اللهَ تَعَالَى يَطْوِي السَّمَوَاتِ بِيَمِينِهِ، وَيَأْخُذُ الْأَرَضِينَ بِيَدِهِ الْأُخْرَى، ثُمَّ يَقُولُ:

أَنَا الْمَلِكُ أَنَا الدَّيَّانُ، أَيْنَ مُلُوكُ الْأَرْضِ ؟

أَيْنَ الْجَبَّارُونَ ؟ أَيْنَ الْمُتَكَبِّرُونَ ؟

Allah, may He be exalted, will fold up the heavens in His Right Hand, and will take the earths in His other Hand, then He will say:

"I am the Sovereign, I am the Judge.

Where are the kings of the earth?

Where are the tyrants Where are the arrogant?''

... وَكَانَ يَوْمًا عَلَى الْكَافِرِينَ عَسِيرًا ﴿٢٦﴾

and it will be a hard Day for the disbelievers.

means it will be very difficult, because it will be the Day of justice and the decisive judgement, as Allah says:

فَذَلِكَ يَوْمَئِذٍ يَوْمٌ عَسِيرٌ

عَلَى الْكَـفِرِينَ غَيْرُ يَسِيرٍ

Truly, that Day will be a hard Day -- Far from easy for the disbelievers! (74:9-10)

This is how the disbelievers will be on the Day of Resurrection.

As for the believers, Allah says:

لاَ يَحْزُنُهُمُ الْفَزَعُ الاٌّكْبَرُ

The greatest terror will not grieve them.