Jami` at-Tirmidhi, Volume 2, Book 11, Hadith 1203 (DarusSalam) ⓘ
Ibn Umar narrated: "A man pronounced the Li'an on his wife, and the Prophet separated the two of them, and he decide that the child belonged to the mother."
أَنْبَأَنَا قُتَيْبَةُ، أَنْبَأَنَا مَالِكُ بْنُ أَنَسٍ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ لاَعَنَ رَجُلٌ امْرَأَتَهُ وَفَرَّقَ النَّبِيُّ صلى الله عليه وسلم بَيْنَهُمَا وَأَلْحَقَ الْوَلَدَ بِالأُمِّ . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ . وَالْعَمَلُ عَلَى هَذَا عِنْدَ أَهْلِ الْعِلْمِ .
also referenced under: Hadith 1203 (Reference) & Book 13, Hadith 30 (In-Book)