People ask you concerning the Hour, say: "The knowledge of it is with Allah only. What do you know? It may be that the Hour is near! (63)Verily, Allah has cursed the disbelievers, and has prepared for them a flaming Fire (64)Wherein they will abide forever, and they will find neither a a protector nor a helper (65)On the Day when their faces will be turned over in the Fire, they will say: "Oh, would that we had obeyed Allah and obeyed the Messenger. (66)And they will say: "Our Lord! Verily, we obeyed our chiefs and our great ones, and they misled us from the way. (67)"Our Lord! Give them double torment and curse them with a mighty curse! (68)

No One knows when the Day of Resurrection will come except Allah

Here Allah tells His Messenger ﷺ that he cannot know when the Hour will come, and if people ask him about that, He instructs him to refer the matter to Allah, may He be exalted, as Allah says in Surat Al-A'raf, even though that was revealed in Makkah and this Surah was revealed in Al-Madinah. Allah continues to tell him to refer this matter to the One Who knows about it, but He tells him that it is at hand, as He says:

وَمَا يُدْرِيكَ لَعَلَّ السَّاعَةَ تَكُونُ قَرِيبًا

(What do you know? It may be that the Hour is near!) This is like the Ayat:

اقْتَرَبَتِ السَّاعَةُ وَانْشَقَّ الْقَمَرُ

(The Hour has drawn near, and the moon has been cleft asunder.)(54:1)

اقْتَرَبَ لِلنَّاسِ حِسَابُهُمْ وَهُمْ فِي غَفْلَةٍ مُعْرِضُونَ

(Draws near for mankind their reckoning, while they turn away in heedlessness.)(21:1)

أَتَىٰ أَمْرُ اللَّهِ فَلَا تَسْتَعْجِلُوهُ ۚ 

(The Event (the Hour) ordained by Allah will come to pass, so seek not to hasten it)(16:1).

The Curse on the Disbelievers and its Eternity and their Regret

Then Allah says:

إِنَّ اللَّهَ لَعَنَ الْكَافِرِينَ

(Verily, Allah has cursed the disbelievers,) means, He has distanced them from His mercy.

وَأَعَدَّ لَهُمْ سَعِيرًا

(and has prepared for them a flaming Fire (Hell).) means, in the Hereafter.

خَالِدِينَ فِيهَا أَبَدًا ۖ 

(Wherein they will abide forever,) means, they will stay there forever and ever, never leaving or finding relief from it.

لَا يَجِدُونَ وَلِيًّا وَلَا نَصِيرًا

(and they will find neither a a protector nor a helper.) means, they will have no saviour to help them or rescue them from their predicament. Then Allah says:

يَوْمَ تُقَلَّبُ وُجُوهُهُمْ فِي النَّارِ يَقُولُونَ يَا لَيْتَنَا أَطَعْنَا اللَّهَ وَأَطَعْنَا الرَّسُولَا

(On the Day when their faces will be turned over in the Fire, they will say: "Oh, would that we had obeyed Allah and obeyed the Messenger.") means, they will be dragged into the Fire on their faces and their faces will be contorted in Hell, and in that state they will wish that they had been among those who had obeyed Allah and His Messenger ﷺ in this world. Allah describes how they will be in the Hereafter:

وَيَوْمَ يَعَضُّ الظَّالِمُ عَلَىٰ يَدَيْهِ يَقُولُ يَا لَيْتَنِي اتَّخَذْتُ مَعَ الرَّسُولِ سَبِيلًا - يَا وَيْلَتَىٰ لَيْتَنِي لَمْ أَتَّخِذْ فُلَانًا خَلِيلًا - لَقَدْ أَضَلَّنِي عَنِ الذِّكْرِ بَعْدَ إِذْ جَاءَنِي ۗ وَكَانَ الشَّيْطَانُ لِلْإِنْسَانِ خَذُولًا

(And the Day when the wrongdoer will bite at his hands, he will say: "Oh! Would that I had taken a path with the Messenger. Ah! Woe to me! Would that I had never taken so-and-so as an intimate friend! He indeed led me astray from the Reminder after it had come to me. And Shaytan is to man ever a deserter in the hour of need.")(25:27-29)

رُبَمَا يَوَدُّ الَّذِينَ كَفَرُوا لَوْ كَانُوا مُسْلِمِينَ 

(How much would those who disbelieved wish that they had been Muslims.)(15:2) And here too, Allah tells us that when they are in this state, they will wish that they had obeyed Allah and His Messenger ﷺ in this world:

وَقَالُوا رَبَّنَا إِنَّا أَطَعْنَا سَادَتَنَا وَكُبَرَاءَنَا فَأَضَلُّونَا السَّبِيلَا

(And they will say: "Our Lord! Verily, we obeyed our chiefs and our great ones, and they misled us from the way.") Tawus said: " 'Our chiefs' means their nobles and 'our great ones' means their scholars."

رَبَّنَا آتِهِمْ ضِعْفَيْنِ مِنَ الْعَذَابِ

(Our Lord! Give them double torment) means, 'for their disbelief and because they mislead us.'

Abu Al-Qasim At-Tabarani recorded from Abu Rafi' that among the names of those who fought with 'Ali, may Allah be pleased with him, was Al-Hajjaj bin 'Amr bin Ghaziyah, and he was the one who, when they met, said; "O people of the Ansar! Do you want to say when we meet our Lord:

رَبَّنَا إِنَّا أَطَعْنَا سَادَتَنَا وَكُبَرَاءَنَا فَأَضَلُّونَا السَّبِيلَا - رَبَّنَا آتِهِمْ ضِعْفَيْنِ مِنَ الْعَذَابِ وَالْعَنْهُمْ لَعْنًا كَبِيرًا

(Our Lord! Verily, we obeyed our chiefs and our great ones, and they misled us from the way. Our Lord! Give them double torment and curse them with a mighty curse!)"