Sahih Muslim 1492
Sahih Muslim · Book 19: The Book of Invoking Curses · Chapter 1
Ibn Shihab narrated about the invokers of curses and the practice of (li'an) based on the authority of Sahl b. Sa'd, of the tribe of Sa'ida. that a person from the Ansar came to Allah's Apostle (ﷺ) and said:
وَحَدَّثَنَا مُحَمَّدُ بْنُ رَافِعٍ ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ ، أَخْبَرَنَا ابْنُ جُرَيْجٍ ، أَخْبَرَنِي ابْنُ شِهَابٍ ، عَنِ الْمُتَلاَعِنَيْنِ، وَعَنِ السُّنَّةِ، فِيهِمَا عَنْ حَدِيثِ، سَهْلِ بْنِ سَعْدٍ أَخِي بَنِي سَاعِدَةَ أَنَّ رَجُلاً، مِنَ الأَنْصَارِ جَاءَ إِلَى النَّبِيِّ صلى الله عليه وسلم فَقَالَ يَا رَسُولَ اللَّهِ أَرَأَيْتَ رَجُلاً وَجَدَ مَعَ امْرَأَتِهِ رَجُلاً وَذَكَرَ الْحَدِيثَ بِقِصَّتِهِ . وَزَادَ فِيهِ فَتَلاَعَنَا فِي الْمَسْجِدِ وَأَنَا شَاهِدٌ . وَقَالَ فِي الْحَدِيثِ فَطَلَّقَهَا ثَلاَثًا قَبْلَ أَنْ يَأْمُرَهُ رَسُولُ اللَّهِ صلى الله عليه وسلم . فَفَارَقَهَا عِنْدَ النَّبِيِّ صلى الله عليه وسلم فَقَالَ النَّبِيُّ صلى الله عليه وسلم " ذَاكُمُ التَّفْرِيقُ بَيْنَ كُلِّ مُتَلاَعِنَيْنِ " .
Allah's Messenger, tell me about the person who found a man with his wife. The remaining part of the hadith is the same (but) with this addition: They invoked curses in the mosque and I was present there. And he narrated in the hadith: He divorced her with three pronouncements before Allah's Messenger (ﷺ) commanded him (to get separation). He separated from her in the presence of Allah's Apostle (ﷺ), whereupon he said: There is a separation between the invokers of curses.