Sunan Abi Dawud, Hadith 2250

Sa’d bin Jubair said I asked Ibn ‘Umar A man accused his wife of adultery? He said “The Apostle of Allaah separated the brother and the sister of Banu Al ‘Ajilan (i.e., husband and wife). He said Allaah knows that one of you is a liar, will one of you repent? He repeated these words three times, but they refused. So he separated them from each other.

حَدَّثَنَا أَحْمَدُ بْنُ مُحَمَّدِ بْنِ حَنْبَلٍ، حَدَّثَنَا إِسْمَاعِيلُ، حَدَّثَنَا أَيُّوبُ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، قَالَ قُلْتُ لاِبْنِ عُمَرَ رَجُلٌ قَذَفَ امْرَأَتَهُ ‏.‏ قَالَ فَرَّقَ رَسُولُ اللَّهِ صلى الله عليه وسلم بَيْنَ أَخَوَىْ بَنِي الْعَجْلاَنِ وَقَالَ ‏ "‏ اللَّهُ يَعْلَمُ أَنَّ أَحَدَكُمَا كَاذِبٌ ‏.‏ فَهَلْ مِنْكُمَا تَائِبٌ ‏" ‏ ‏.‏ يُرَدِّدُهَا ثَلاَثَ مَرَّاتٍ فَأَبَيَا فَفَرَّقَ بَيْنَهُمَا ‏.‏

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also referenced under: Hadith 2258 (DarusSalam)