• أَعْثَرْنَا
• عُثِرَ

Appears 2 times in the Quran.

1. 5:107 فَإِنْ عُثِرَ عَلَىٰٓ أَنَّهُمَا ٱسْتَحَقَّآ إِثْمًا فَـَٔاخَرَانِ يَقُومَانِ مَقَامَهُمَا مِنَ ٱلَّذِينَ ٱسْتَحَقَّ عَلَيْهِمُ ٱلْأَوْلَيَٰنِ فَيُقْسِمَانِ بِٱللَّهِ لَشَهَٰدَتُنَآ أَحَقُّ مِن شَهَٰدَتِهِمَا وَمَا ٱعْتَدَيْنَآ إِنَّآ إِذًا لَّمِنَ ٱلظَّٰلِمِينَ

   Then if it becomes known that they both have been guilty of a sin, two others shall stand up in their place from among those who have a claim against them, the two nearest in kin; so they two should swear by Allah: Certainly our testimony is truer than the testimony of those two, and we have not exceeded the limit, for then most surely we should be of the unjust.
   

2. 18:21 وَكَذَٰلِكَ أَعْثَرْنَا عَلَيْهِمْ لِيَعْلَمُوٓا۟ أَنَّ وَعْدَ ٱللَّهِ حَقٌّ وَأَنَّ ٱلسَّاعَةَ لَا رَيْبَ فِيهَآ إِذْ يَتَنَٰزَعُونَ بَيْنَهُمْ أَمْرَهُمْ فَقَالُوا۟ ٱبْنُوا۟ عَلَيْهِم بُنْيَٰنًا رَّبُّهُمْ أَعْلَمُ بِهِمْ قَالَ ٱلَّذِينَ غَلَبُوا۟ عَلَىٰٓ أَمْرِهِمْ لَنَتَّخِذَنَّ عَلَيْهِم مَّسْجِدًا

   And thus did We make (men) to get knowledge of them that they might know that Allah's promise is true and that as for the hour there is no doubt about it. When they disputed among themselves about their affair and said: Erect an edifice over them-- their Lord best knows them. Those who prevailed in their affair said: We will certainly raise a masjid over them.