The Quran

وَيَومَ تَقومُ السّاعَةُ يُقسِمُ المُجرِمونَ ما لَبِثوا غَيرَ ساعَةٍ ۚ كَذٰلِكَ كانوا يُؤفَكونَ

Muhammad Asad

[He it is who will cause you to die, and in time will resurrect you.]¹ And when the Last Hour dawns, those who had been lost in sin will swear that they had not tarried [on earth] longer than an hour: thus were they wont to delude themselves [all their lives]!²

This interpolation - the meaning of which is elliptically implied here - shows the connection of the present passage with the preceding one, as well as with verses 11-16 and 27.
The illusory character of man's earthbound concept of "time" is brought out in the Quran in several places. In the above context stress is laid, firstly, on the relativity of this concept - i.e., on the infinitesimal shortness of our life on earth as compared with the timeless duration of life in the hereafter (cf., for instance, 10:45 or 17:52) - and, secondly, on the resurrected sinners' self-deluding excuse that their life on earth had been too short to allow them to realize their errors and mend their ways. It is to this second aspect of the problem that the Qur'an alludes in the "words, "thus were they wont to delude themselves" (lit., "to be turned away", i.e., from the truth). For an explanation of the verb yu'fikun, see surah 5, note 90.