Qur'an 5:107

فَإِنْ عُثِرَ عَلَىٰٓ أَنَّهُمَا ٱسْتَحَقَّآ إِثْمًا فَـَٔاخَرَانِ يَقُومَانِ مَقَامَهُمَا مِنَ ٱلَّذِينَ ٱسْتَحَقَّ عَلَيْهِمُ ٱلْأَوْلَيَـٰنِ فَيُقْسِمَانِ بِٱللَّهِ لَشَهَـٰدَتُنَآ أَحَقُّ مِن شَهَـٰدَتِهِمَا وَمَا ٱعْتَدَيْنَآ إِنَّآ إِذًا لَّمِنَ ٱلظَّـٰلِمِينَ

But then, if it is afterwards ascertained that both of them merit (the suspicion of) sin, let two others take their place of those nearly concerned, and let them swear by Allah, (saying): Verily our testimony is truer than their testimony and we have not transgressed (the bounds of duty), for them indeed we should be of the evil-doers.