• صَدَفَ
• صَّدَفَيْن
• يَصْدِفُونَ

Appears 3 times in the Quran.

1. 6:46 قُلْ أَرَءَيْتُمْ إِنْ أَخَذَ ٱللَّهُ سَمْعَكُمْ وَأَبْصَٰرَكُمْ وَخَتَمَ عَلَىٰ قُلُوبِكُم مَّنْ إِلَٰهٌ غَيْرُ ٱللَّهِ يَأْتِيكُم بِهِ ٱنظُرْ كَيْفَ نُصَرِّفُ ٱلْءَايَٰتِ ثُمَّ هُمْ يَصْدِفُونَ

   Say: Have you considered that if Allah takes away your hearing and your sight and sets a seal on your hearts, who is the god besides Allah that can bring it to you? See how We repeat the communications, yet they turn away.
   

2. 6:157 أَوْ تَقُولُوا۟ لَوْ أَنَّآ أُنزِلَ عَلَيْنَا ٱلْكِتَٰبُ لَكُنَّآ أَهْدَىٰ مِنْهُمْ فَقَدْ جَآءَكُم بَيِّنَةٌ مِّن رَّبِّكُمْ وَهُدًى وَرَحْمَةٌ فَمَنْ أَظْلَمُ مِمَّن كَذَّبَ بِـَٔايَٰتِ ٱللَّهِ وَصَدَفَ عَنْهَا سَنَجْزِى ٱلَّذِينَ يَصْدِفُونَ عَنْ ءَايَٰتِنَا سُوٓءَ ٱلْعَذَابِ بِمَا كَانُوا۟ يَصْدِفُونَ

   Or lest you should say: If the Book had been revealed to us, we would certainly have been better guided than they, so indeed there has come to you clear proof from your Lord, and guidance and mercy. Who then is more unjust than he who rejects Allah's communications and turns away from them? We will reward those who turn away from Our communications with an evil chastisement because they turned away.
   

3. 18:96 ءَاتُونِى زُبَرَ ٱلْحَدِيدِ حَتَّىٰٓ إِذَا سَاوَىٰ بَيْنَ ٱلصَّدَفَيْنِ قَالَ ٱنفُخُوا۟ حَتَّىٰٓ إِذَا جَعَلَهُۥ نَارًا قَالَ ءَاتُونِىٓ أُفْرِغْ عَلَيْهِ قِطْرًا

   Bring me blocks of iron; until when he had filled up the space between the two mountain sides, he said: Blow, until when he had made it (as) fire, he said: Bring me molten brass which I may pour over it.