Qur'an 45:32 · Al-Jaathiya

وَإِذَا قِيلَ إِنَّ وَعْدَ ٱللَّهِ حَقٌّۭ وَٱلسَّاعَةُ لَا رَيْبَ فِيهَا قُلْتُم مَّا نَدْرِى مَا ٱلسَّاعَةُ إِن نَّظُنُّ إِلَّا ظَنًّۭا وَمَا نَحْنُ بِمُسْتَيْقِنِينَ

(32) And when it was said, 'Indeed, the promise of Allāh is truth and the Hour [is coming] - no doubt about it,' you said, 'We know not what is the Hour. We assume only assumption, and we are not convinced.'"