Quran 45:32 Al-Jathiyah, ayah 32 of 37

وَإِذَا قِيلَ إِنَّ وَعْدَ ٱللَّهِ حَقٌّ وَٱلسَّاعَةُ لَا رَيْبَ فِيهَا قُلْتُم مَّا نَدْرِى مَا ٱلسَّاعَةُ إِن نَّظُنُّ إِلَّا ظَنًّا وَمَا نَحْنُ بِمُسْتَيْقِنِينَ ۝٣٢

45:32 And when it was said: Lo! Allah's promise is the truth, and there is no doubt of the Hour's coming, ye said: We know not what the Hour is. We deem it naught but a conjecture, and we are by no means convinced.