Sahih (Sahih al-Bukhari)
حَدَّثَنِي يَحْيَى بْنُ قَزَعَةَ، حَدَّثَنَا مَالِكٌ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما أَنَّ رَجُلاً، لاَعَنَ امْرَأَتَهُ فِي زَمَنِ النَّبِيِّ صلى الله عليه وسلم وَانْتَفَى مِنْ وَلَدِهَا فَفَرَّقَ النَّبِيُّ صلى الله عليه وسلم بَيْنَهُمَا، وَأَلْحَقَ الْوَلَدَ بِالْمَرْأَةِ.
Narrated Ibn `Umar:A man and his wife had a case of Lian (or Mula'ana) during the lifetime of the Prophet (ﷺ) and the man denied the paternity of her child. The Prophet (ﷺ) gave his verdict for their separation (divorce) and then the child was regarded as belonging to the wife only