[But they urge you to hasten the punishment.] This is on their part a form of denial and mockery, as if it will not come to pass. [And Allah will never fail in His promise.] Al-Hasan's explanation: It means their destruction at the Hour before the punishment of the Hereafter. [And indeed, a day with your Lord is like a thousand years of those which you count.] A day from the days of the Hereafter is like a thousand years of the days of this world.
﴿ويستعجلونك بِالْعَذَابِ﴾ وَذَلِكَ مِنْهُمْ تَكْذِيبٌ وَاسْتِهْزَاءٌ بِأَنَّهُ لَا يَكُونُ ﴿وَلَنْ يُخْلِفَ الله وعده﴾ تَفْسِيرُ الْحَسَنِ: يَعْنِي: هَلَاكَهُمْ بِالسَّاعَةِ قَبْلَ عَذَابِ الْآخِرَةِ. ﴿وَإِنَّ يَوْمًا عِنْدَ رَبِّكَ كَأَلْفِ سَنَةٍ مِمَّا تَعدونَ﴾ يَوْمُ مِنْ أَيَّامِ الْآخِرَةِ كَأَلْفِ سنة من أَيَّام الدُّنْيَا