Muwatta Imam Malik Book of Wills and Testaments, Hadith 6

Malik related to me that Yahya ibn Said said that he heard al- Qasim ibn Muhammad say, "A woman of the Ansar was married to Umar ibn al-Khattab. She bore Asim ibn Umar to him, and then he separated from her. Umar came to Quba and found his son Asim playing in the courtyard of the mosque. He took him by the arm and placed him before him on his mount. The grandmother of the child saw him and argued with Umar about the child so they went to Abu Bakr as-Siddiq. Umar said, 'My son.' The woman said, 'My son.' Abu Bakr said, 'Do not interfere between a child and its mother.' Umar did not repeat his words."
Yahya said that he heard Malik say, "This is what I would have done in that situation."

وَحَدَّثَنِي مَالِكٌ، عَنْ يَحْيَى بْنِ سَعِيدٍ، أَنَّهُ قَالَ سَمِعْتُ الْقَاسِمَ بْنَ مُحَمَّدٍ، يَقُولُ كَانَتْ عِنْدَ عُمَرَ بْنِ الْخَطَّابِ امْرَأَةٌ مِنَ الأَنْصَارِ فَوَلَدَتْ لَهُ عَاصِمَ بْنَ عُمَرَ ثُمَّ إِنَّهُ فَارَقَهَا فَجَاءَ عُمَرُ قُبَاءً فَوَجَدَ ابْنَهُ عَاصِمًا يَلْعَبُ بِفِنَاءِ الْمَسْجِدِ فَأَخَذَ بِعَضُدِهِ فَوَضَعَهُ بَيْنَ يَدَيْهِ عَلَى الدَّابَّةِ فَأَدْرَكَتْهُ جَدَّةُ الْغُلاَمِ فَنَازَعَتْهُ إِيَّاهُ حَتَّى أَتَيَا أَبَا بَكْرٍ الصِّدِّيقَ فَقَالَ عُمَرُ ابْنِي . وَقَالَتِ الْمَرْأَةُ ابْنِي . فَقَالَ أَبُو بَكْرٍ خَلِّ بَيْنَهَا وَبَيْنَهُ . قَالَ فَمَا رَاجَعَهُ عُمَرُ الْكَلاَمَ . قَالَ وَسَمِعْتُ مَالِكًا يَقُولُ وَهَذَا الأَمْرُ الَّذِي آخُذُ بِهِ فِي ذَلِكَ .