Sahih Muslim , Book 19, Hadith 2 (In-Book) ⓘ

Sahl b. Sa'd reported.. 'Uwaimir al-Ansari (Allah be pleased with him) from Banu'l-'Ajlan came to 'Asim b. 'Adi (Allah be pleased with him) the remaining part of the hadith is the same and it was also reecorded in it: " And subsequebtly the separation became the practice of al-Mutala'inain." And this addition was also made:" She was pregnant and her son was ascribed to her, and it became customary that such (a son) would inherit her and she would inherit him in the share prescribed by Allah for her.

وَحَدَّثَنِي حَرْمَلَةُ بْنُ يَحْيَى، أَخْبَرَنَا ابْنُ وَهْبٍ، أَخْبَرَنِي يُونُسُ، عَنِ ابْنِ شِهَابٍ، أَخْبَرَنِي سَهْلُ بْنُ سَعْدٍ الأَنْصَارِيُّ، أَنَّ عُوَيْمِرًا الأَنْصَارِيَّ، مِنْ بَنِي الْعَجْلاَنِ أَتَى عَاصِمَ بْنَ عَدِيٍّ ‏.‏ وَسَاقَ الْحَدِيثَ بِمِثْلِ حَدِيثِ مَالِكٍ وَأَدْرَجَ فِي الْحَدِيثِ قَوْلَهُ وَكَانَ فِرَاقُهُ إِيَّاهَا بَعْدُ سُنَّةً فِي الْمُتَلاَعِنَيْنِ ‏.‏ وَزَادَ فِيهِ قَالَ سَهْلٌ فَكَانَتْ حَامِلاً فَكَانَ ابْنُهَا يُدْعَى إِلَى أُمِّهِ ‏.‏ ثُمَّ جَرَتِ السُّنَّةُ أَنَّهُ يَرِثُهَا وَتَرِثُ مِنْهُ مَا فَرَضَ اللَّهُ لَهَا ‏.‏