Sahih al-Bukhari 7166
Sahih al-Bukhari · Book 93: Judgments (Ahkaam) · Whoever gave judgements of Li'an in the mosque
Narrated Sahl:
حَدَّثَنَا يَحْيَى ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ ، أَخْبَرَنَا ابْنُ جُرَيْجٍ ، أَخْبَرَنِي ابْنُ شِهَابٍ ، عَنْ سَهْلٍ ، أَخِي بَنِي سَاعِدَةَ أَنَّ رَجُلاً، مِنَ الأَنْصَارِ جَاءَ إِلَى النَّبِيِّ صلى الله عليه وسلم فَقَالَ أَرَأَيْتَ رَجُلاً وَجَدَ مَعَ امْرَأَتِهِ رَجُلاً، أَيَقْتُلُهُ فَتَلاَعَنَا فِي الْمَسْجِدِ وَأَنَا شَاهِدٌ .
(the brother of Bani Sa`ida) A man from the Ansar came to the Prophet (ﷺ) and said, "If a man finds another man sleeping with his wife, should he kill him?" That man and his wife then did Lian in the mosque while I was present.