Surah Saba, Ayah 6

The Hour will come so that each Person will be rewarded or punished in accordance with His Deeds

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

Verse 6: وَيَرَ‌ى الَّذِينَ أُوتُوا الْعِلْمَ (34:6) talks about believers in contrast with those who denied the coming of the Qiyamah. The former had put their faith in it and became the beneficiaries of the knowledge given by Allah Ta’ ala to the Holy Prophet ﷺ by revelation.

The addressees of the Quran were not disbelievers in the Day of Judgement. It was just that they did not believe that Judgement Day would bring them humiliation and punishment. The world they lived in appeared safe to them and they could not, therefore, understand how they would be in jeopardy on reaching the world Hereafter. This truth about life and the Universe is found in all divine scriptures. It is the Quran’s mission to reveal this reality in its pure and unadulterated form. Now, those who take a stand in opposition to this mission are indulging in the most improper bravado. Before God, they will be treated as deserving of the severest punishment.