Here Allah tells us how the disbelievers and heretics denied that the Hour will come, and mocked the Messenger ﷺ for speaking of it.

وَقَالَ الَّذِينَ كَفَرُواْ هَلْ نَدُلُّكُمْ عَلَى رَجُلٍ يُنَبِّئُكُمْ إِذَا مُزِّقْتُمْ كُلَّ مُمَزَّقٍ

(Those who disbelieve say: "Shall we direct you to a man who will tell you (that) when you have become fully disintegrated into dust with full dispersion...") means, when your bodies have disintegrated into the earth and dispersed without a trace,

إِنَّكُمْ

(then you) means, after this has happened,

لَفِى خَلْقٍ جَدِيدٍ

(will be created (again) anew) means, you will be restored to life and will receive provision anew. `By telling us this, he is doing one of two things: either he is deliberately fabricating something and saying that Allah has revealed it to him, or he is not doing it deliberately, but he is deluded as crazy and insane people are.' They said:

أَفْتَرَى عَلَى اللَّهِ كَذِباً أَم بِهِ جِنَّةٌ

(Has he invented a lie against Allah, or is there a madness in him) Allah said, refuting their words:

بَلِ الَّذِينَ لاَ يُؤْمِنُونَ بِالاٌّخِرَةِ فِى الْعَذَابِ وَالضَّلَـلِ الْبَعِيدِ

(Nay, but those who disbelieve in the Hereafter are (themselves) in a torment, and in far error.) meaning, the matter is not as they claim or as they think; on the contrary, Muhammad ﷺ is the one who is telling the truth, and is righteous and wise; he is the one who has brought the truth, and they are the foolish and ignorant liars.

فِى الْعَذَابِ

are themselves( in a torment, means, their disbelief, which will lead them to the torment of Allah.

وَالضَّلَـلِ الْبَعِيدِ

(and in far error.) far from the truth in this world. Then Allah warns them of His power in the creation of heavens and earth, as He says:

أَفَلَمْ يَرَوْاْ إِلَى مَا بَيْنَ أَيْدِيهِمْ وَمَا خَلْفَهُمْ مِّنَ السَّمَآءِ وَالاٌّرْضِ

(See they not what is before them and what is behind them, of the heaven and the earth) meaning, wherever they go, in whatever direction, the heavens are above them and the earth is beneath them. This is like the Ayah:

وَالسَّمَآءَ بَنَيْنَـهَا بِأَيْدٍ وَإِنَّا لَمُوسِعُونَ - وَالاٌّرْضَ فَرَشْنَـهَا فَنِعْمَ الْمَـهِدُونَ

(With Hands did We construct the heaven. Verily, We are Able to extend the vastness of space thereof. And We have spread out the earth; how Excellent Spreader (thereof) are We!) (51:47-48)

إِن نَّشَأْ نَخْسِفْ بِهِمُ الاٌّرْضَ أَوْ نُسْقِطْ عَلَيْهِمْ كِسَفاً مِّنَ السَّمَآءِ

(If We will, We shall sink the earth with them, or cause a piece of the heaven to fall upon them.) means, `if We wished, We could do that to them because of their wrongdoing and Our power over them, but We delay it because We are Patient and Forgiving.' Then Allah says:

إِنَّ فِى ذَلِكَ لاّيَةً لِّكُلِّ عَبْدٍ مُّنِيبٍ

(Verily, in this is a sign for every Munib servant.) Ma`mar narrating from Qatadah, said that Al-Munib means every one who repents. Sufyan narrated from Qatadah, that Al-Munib is the one who turns to Allah. This means that in looking at the creation of the heavens and the earth, there is a sign for every servant who is intelligent and wise and who turns towards Allah. There is a sign of the Allah's ability to recreate bodies and bring about the Resurrection, because the One Who was able to create these heavens -- with their vast reaches of space, and this earth, as deep and vast as it is -- is able to recreate bodies and revive decayed bones. This is like the Ayat:

أَوَلَـيْسَ الَذِى خَلَقَ السَّمَـوتِ وَالاٌّرْضَ بِقَـدِرٍ عَلَى أَن يَخْلُقَ مِثْلَهُم بَلَى

(Is not He Who created the heavens and the earth, Able to create the like of them Yes, indeed!) (36:81)

لَخَلْقُ السَّمَـوَتِ وَالاٌّرْضِ أَكْـبَرُ مِنْ خَلْقِ النَّاسِ وَلَـكِنَّ أَكْـثَرَ النَّاسِ لاَ يَعْلَمُونَ

(The creation of the heavens and the earth is indeed greater than the creation of mankind; yet, most of mankind know not. ) (40:57)