• فَتْرَة
• يُفَتَّرُ
• يَفْتُرُونَ

Appears 3 times in the Quran.

1. 5:19 يَٰٓأَهْلَ ٱلْكِتَٰبِ قَدْ جَآءَكُمْ رَسُولُنَا يُبَيِّنُ لَكُمْ عَلَىٰ فَتْرَةٍ مِّنَ ٱلرُّسُلِ أَن تَقُولُوا۟ مَا جَآءَنَا مِنۢ بَشِيرٍ وَلَا نَذِيرٍ فَقَدْ جَآءَكُم بَشِيرٌ وَنَذِيرٌ وَٱللَّهُ عَلَىٰ كُلِّ شَىْءٍ قَدِيرٌ

   O followers of the Book! indeed Our Messenger has come to you explaining to you after a cessation of the (mission of the) messengers, lest you say: There came not to us a giver of good news or a warner, so indeed there has come to you a giver of good news and a warner; and Allah has power over all things.
   

2. 21:20 يُسَبِّحُونَ ٱلَّيْلَ وَٱلنَّهَارَ لَا يَفْتُرُونَ

   They glorify (Him) by night and day; they are never languid.
   

3. 43:75 لَا يُفَتَّرُ عَنْهُمْ وَهُمْ فِيهِ مُبْلِسُونَ

   It shall not be abated from them and they shall therein be despairing.