The Terrors of the Day of Resurrection, and how the Wrongdoers will wish that They had taken a Path with the Messenger
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:
تَشَقَّقُ السَّمَاءُ بِالْغَمَامِ (The sky will break open with a cloud - 25:25). The explanation of the verse is that the sky will rip apart and a sort of liquid cloud will descend from it which will be carrying angels with it. This cloud will look like a canopy descending from the sky and will be bearing Allah Ta’ ala's refulgence surrounded by angels. This will precede the beginning of the reckoning and the sky will rip open only to make an opening. It will not be the same ripping as the one when the sur (صُور) will be blown to finish off the earth and the sky, because this descension of the cloud will take place after the second blowing of the sur (صُور) when the earth and the sky would have taken the new shape. (Bayan u1-Qur’ an)
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 24–30
Those who demand, as a precondition, the physical appearance of God and His angels, before they accept a missionary’s message, are not really sincere about it. Frivolous in their attitude, they do not know the implication or meaning of the appearance of God and His angels. The fact is that it is only when the Truth is revealed through a preacher of truth that they will have an opportunity to accept it. The moment Truth shows itself by the appearance of God and His angels, it will be the time for reckoning and judgement, and not the time for acceptance. Many people labour under the misapprehension that on Judgement Day, when God asks them about their deeds, they will escape His verdict by showing off some good deed of theirs and by saying that they have the patronage of some saint or the other. But, on Judgement Day, all this wishful thinking will vanish into thin air, as if a drop of water had fallen on a red hot iron sheet and disappeared. On that Day, only righteous deeds will be of avail, and not false hopes.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.