وَإِذَا لَقُوا۟ ٱلَّذِينَ ءَامَنُوا۟ قَالُوٓا۟ ءَامَنَّا وَإِذَا خَلَوْا۟ إِلَىٰ شَيَـٰطِينِهِمْ قَالُوٓا۟ إِنَّا مَعَكُمْ إِنَّمَا نَحْنُ مُسْتَهْزِءُونَ

And when they meet those who believe, they say, "We believe"; but when they are alone with their evil ones, they say, "Indeed, we are with you; we were only mockers."

Al-Baqarah 14

وَمِنَ ٱلنَّاسِ مَن يَقُولُ ءَامَنَّا بِٱللَّهِ وَبِٱلْيَوْمِ ٱلْـَٔاخِرِ وَمَا هُم بِمُؤْمِنِينَ

And of the people are some who say, "We believe in Allāh and the Last Day," but they are not believers.

Al-Baqarah 8

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

وَمَآ أَصَـٰبَكُمْ يَوْمَ ٱلْتَقَى ٱلْجَمْعَانِ فَبِإِذْنِ ٱللَّهِ وَلِيَعْلَمَ ٱلْمُؤْمِنِينَ

And what struck you on the day the two armies met [at Uḥud] was by permission of Allāh that He might make evident the [true] believers

Ali 'Imran 166

ٱلَّذِينَ قَالُوا۟ لِإِخْوَٰنِهِمْ وَقَعَدُوا۟ لَوْ أَطَاعُونَا مَا قُتِلُوا۟ ۗ قُلْ فَٱدْرَءُوا۟ عَنْ أَنفُسِكُمُ ٱلْمَوْتَ إِن كُنتُمْ صَـٰدِقِينَ

Those who said about their brothers while sitting [at home], "If they had obeyed us, they would not have been killed." Say, "Then prevent death from yourselves, if you should be truthful."

Ali 'Imran 168