وَقَالَ ٱلَّذِينَ لَا يَعْلَمُونَ لَوْلَا يُكَلِّمُنَا ٱللَّهُ أَوْ تَأْتِينَآ ءَايَةٌ ۗ كَذَٰلِكَ قَالَ ٱلَّذِينَ مِن قَبْلِهِم مِّثْلَ قَوْلِهِمْ ۘ تَشَـٰبَهَتْ قُلُوبُهُمْ ۗ قَدْ بَيَّنَّا ٱلْـَٔايَـٰتِ لِقَوْمٍ يُوقِنُونَ

Those who do not know say, "Why does Allāh not speak to us or there come to us a sign?" Thus spoke those before them like their words. Their hearts resemble each other. We have shown clearly the signs to a people who are certain [in faith].

Al-Baqarah 118

وَلَوْ أَنَّهُمْ ءَامَنُوا۟ وَٱتَّقَوْا۟ لَمَثُوبَةٌ مِّنْ عِندِ ٱللَّهِ خَيْرٌ ۖ لَّوْ كَانُوا۟ يَعْلَمُونَ

And if they had believed and feared Allāh, then the reward from Allāh would have been [far] better, if they only knew.

Al-Baqarah 103

وَإِن كُنتُمْ فِى رَيْبٍ مِّمَّا نَزَّلْنَا عَلَىٰ عَبْدِنَا فَأْتُوا۟ بِسُورَةٍ مِّن مِّثْلِهِۦ وَٱدْعُوا۟ شُهَدَآءَكُم مِّن دُونِ ٱللَّهِ إِن كُنتُمْ صَـٰدِقِينَ

And if you are in doubt about what We have sent down [i.e., the Qur’ān] upon Our Servant [i.e., Prophet Muḥammad (ﷺ)], then produce a sūrah the like thereof and call upon your witnesses [i.e., supporters] other than Allāh, if you should be truthful.

Al-Baqarah 23

ٱلْحَقُّ مِن رَّبِّكَ ۖ فَلَا تَكُونَنَّ مِنَ ٱلْمُمْتَرِينَ

The truth is from your Lord, so never be among the doubters.

Al-Baqarah 147

وَلِيَعْلَمَ ٱلَّذِينَ نَافَقُوا۟ ۚ وَقِيلَ لَهُمْ تَعَالَوْا۟ قَـٰتِلُوا۟ فِى سَبِيلِ ٱللَّهِ أَوِ ٱدْفَعُوا۟ ۖ قَالُوا۟ لَوْ نَعْلَمُ قِتَالًا لَّٱتَّبَعْنَـٰكُمْ ۗ هُمْ لِلْكُفْرِ يَوْمَئِذٍ أَقْرَبُ مِنْهُمْ لِلْإِيمَـٰنِ ۚ يَقُولُونَ بِأَفْوَٰهِهِم مَّا لَيْسَ فِى قُلُوبِهِمْ ۗ وَٱللَّهُ أَعْلَمُ بِمَا يَكْتُمُونَ

And that He might make evident those who are hypocrites. For it was said to them, "Come, fight in the way of Allāh or [at least] defend." They said, "If we had known [there would be] battle, we would have followed you." They were nearer to disbelief that day than to faith, saying with their mouths what was not in their hearts. And Allāh is most knowing of what they conceal -

Ali 'Imran 167