This is one of three Ayat -- there is no fourth -- where Allah commands His Messenger to swear by His Almighty Lord that the resurrection will surely come, because the stubborn followers of disbelief denied that it would happen. One of these Ayat is in Surah Yunus, where Allah says:

وَيَسْتَنْبِئُونَكَ أَحَقٌّ هُوَ قُلْ إِى وَرَبِّى إِنَّهُ لَحَقٌّ وَمَآ أَنتُمْ بِمُعْجِزِينَ

(And they ask you to inform them (saying): "Is it true" Say: "Yes! By my Lord! It is the very truth! and you cannot escape it!") (10:53). The second of these Ayat is this one:

وَقَالَ الَّذِينَ كَفَرُواْ لاَ تَأْتِينَا السَّاعَةُ قُلْ بَلَى وَرَبِّى لَتَأْتِيَنَّكُمْ

(Those who disbelieve say: "The Hour will not come to us." Say: "Yes, by my Lord, it will come to you..."). And the third of them appears in Surat At-Taghabun, where Allah says:

زَعَمَ الَّذِينَ كَفَرُواْ أَن لَّن يُبْعَثُواْ قُلْ بَلَى وَرَبِّى لَتُبْعَثُنَّ ثُمَّ لَتُنَبَّؤُنَّ بِمَا عَمِلْتُمْ وَذَلِكَ عَلَى اللَّهِ يَسِيرٌ

(The disbelievers pretend that they will never be resurrected (for reckoning). Say: "Yes! By my Lord, you will certainly be resurrected, then you will be informed of what you did; and that is easy for Allah") (64:7). And Allah says here:

قُلْ بَلَى وَرَبِّى لَتَأْتِيَنَّكُمْ

(Say: "Yes, by my Lord, it will come to you...") Then Allah is described in a manner that affirms that:

عَـلِمِ الْغَيْبِ لاَ يَعْزُبُ عَنْهُ مِثْقَالُ ذَرَّةٍ فِى السَّمَـوَتِ وَلاَ فِى الاٌّرْضِ وَلاَ أَصْغَرُ مِن ذَلِكَ وَلاَ أَكْبَرُ إِلاَّ فِى كِتَـبٍ مُّبِينٍ

(the All-Knower of the Unseen, not even the weight of a speck of dust or less than that or greater escapes His knowledge in the heavens or in the earth but it is in a Clear Book.) Mujahid and Qatadah said, "Nothing is hidden or concealed from Him." In other words, everything is encompassed by His knowledge, and nothing is hidden from Him. Even though bones may be scattered and disintegrate, He knows where they have gone and where they have dispersed, then He will bring them back just as He created them in the first place, because He has knowledge of all things. Then Allah tells us of His wisdom in re-creating bodies and bringing about the Hour, as He says:

لِّيَجْزِىَ الَّذِينَ ءَامَنُواْ وَعَمِلُواْ الصَّـلِحَـتِ أُوْلَـئِكَ لَهُمْ مَّغْفِرَةٌ وَرِزْقٌ كَرِيمٌ وَالَّذِينَ سَعَوْا فِى ءَايَـتِنَا مُعَاجِزِينَ

(That He may recompense those who believe and do righteous good deeds. Those, theirs is forgiveness and generous provision. But those who strive against Our Ayat to frustrate them) meaning, those who try to turn others away from the path of Allah and who disbelieve His Messengers,

أُوْلَـئِكَ لَهُمْ عَذَابٌ مِّن رِّجْزٍ أَلِيمٌ

(those, for them will be a severe painful torment.) This means, He will bestow His favor upon the blessed, who are the believers, and will punish the doomed, who are the disbelievers. This is like the Ayah:

لاَ يَسْتَوِى أَصْحَـبُ النَّارِ وَأَصْحَـبُ الْجَنَّةِ أَصْحَـبُ الْجَنَّةِ هُمُ الْفَآئِزُونَ

(Not equal are the dwellers of the Fire and the dwellers of the Paradise. It is the dwellers of Paradise that will be successful.) (59:20)

أَمْ نَجْعَلُ الَّذِينَ ءَامَنُواْ وَعَمِلُواْ الصَّـلِحَـتِ كَالْمُفْسِدِينَ فِى الاٌّرْضِ أَمْ نَجْعَلُ الْمُتَّقِينَ كَالْفُجَّارِ

(Shall We treat those who believe and do righteous good deeds like those who cause mischief on the earth Or shall We treat those who have Taqwa as the evildoers) (38:28)

وَيَرَى الَّذِينَ أُوتُواْ الْعِلْمَ الَّذِى أُنزِلَ إِلَيْكَ مِن رَّبِّكَ هُوَ الْحَقَّ

(And those who have been given knowledge see that what is revealed to you from your Lord is the truth,) This is another kind of wisdom, following on from the one before, which is that when those who believed in what was revealed to the Messengers see the onset of the Hour and how the righteous and the wicked will be rewarded and punished respectively, which they knew of beforehand in this world from the Books of Allah and which they are now seeing with their own eyes, they will say:

لَقَدْ جَآءَتْ رُسُلُ رَبِّنَا بِالْحَقِّ

(Indeed, the Messengers of our Lord did come with the truth) (7:43). And it will be said:

هَذَا مَا وَعَدَ الرَّحْمـنُ وَصَدَقَ الْمُرْسَلُونَ

(This is what the Most Gracious had promised, and the Messengers spoke truth!) 36:52

لَقَدْ لَبِثْتُمْ فِى كِتَـبِ اللَّهِ إِلَى يَوْمِ الْبَعْثِ فَهَـذَا يَوْمُ الْبَعْثِ

(Indeed you have stayed according to the decree of Allah, until the Day of Resurrection; so this is the Day of Resurrection) (30:56),

وَيَرَى الَّذِينَ أُوتُواْ الْعِلْمَ الَّذِى أُنزِلَ إِلَيْكَ مِن رَّبِّكَ هُوَ الْحَقَّ وَيَهْدِى إِلَى صِرَاطِ الْعَزِيزِ الْحَمِيدِ

(And those who have been given knowledge see that what is revealed to you from your Lord is the truth, and that it guides to the path of the Exalted in might, Owner of all praise.) The Exalted in might is the One Who is All-Powerful, Whom none can overwhelm or resist, but He subjugates and controls all things. The Owner of All praise is the One Who, in all His words, deeds, laws and decrees, is deserving of praise, may He be glorified and exalted.