إِنَّ ٱلسَّاعَةَ لَـَٔاتِيَةٌ لَّا رَيْبَ فِيهَا وَلَـٰكِنَّ أَكْثَرَ ٱلنَّاسِ لَا يُؤْمِنُونَ Qur’an Ghafir (40:59)Inna a l ss a AAata la a tiyatun l a rayba feeh a wal a kinna akthara a l nn a si l a yuminoon a
I.e., refuse to admit to themselves that the world as they know it could ever come to an end: which is another aspect of the "overweening conceit" spoken of in verse {56} above.
"The Hour" is the crown and consummation of man's life on this earth,-the gateway to the Hereafter.