Musnad Ahmad 398
It was narrated that Sa`eed said:
I said to IbnʼUmar (رضي الله عنه): What about a man who engaged in li`an with his wife? He said: The Messenger of Allah (ﷺ)  would separate them - and he mentioned the hadeeth.
حَدَّثَنَا سُفْيَانُ، عَنْ أَيُّوبَ، عَنْ سَعِيدٍ، قَالَ قُلْتُ لِابْنِ عُمَرَ رَضِيَ اللَّهُ عَنْهُ رَجُلٌ لَاعَنَ امْرَأَتَهُ فَقَالَ فَرَّقَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ بَيْنَهُمَا وَذَكَرَ الْحَدِيثَ‏.‏