وَمَا أَظُنُّ السَّاعَةَ قَايِمَةً
...
"And I do not think the Hour will ever come..."
meaning, will ever happen
...
وَلَيِن رُّدِدتُّ إِلَى رَبِّي لاََجِدَنَّ خَيْرًا مِّنْهَا مُنقَلَبًا
and if indeed I am brought back to my Lord, I surely shall find better than this when I return to Him.
meaning, `if there is a Hereafter and a return to Allah, then I will have a better share than this with my Lord, for if it were not that I am dear to Him, He would not have given me all this.'
As Allah says elsewhere:
وَلَيِن رُّجِّعْتُ إِلَى رَبِّى إِنَّ لِى عِندَهُ لَلْحُسْنَى
But if I am brought back to my Lord, surely there will be for me the best with Him. (41:50)
أَفَرَأَيْتَ الَّذِى كَفَرَ بِـَايَـتِنَا وَقَالَ لاوتَيَنَّ مَالاً وَوَلَداً
Have you seen him who disbelieved in Our Ayat and said: "I shall certainly be given wealth and children (if I will be alive again)." (19:77)
He took it for granted that Allah would give him this, without any sound evidence for that.
The reason why this Ayah was revealed was because of Al-`As bin Wa'il, as we will explain in the appropriate place, if Allah wills. In Allah we put our trust.