Muwatta Imam Malik Book of Judgements, Hadith 22
Malik related to me from Yahya ibn Said from Sulayman ibn Yasar that Umar ibn al-Khattab used to attach the children of the Jahiliyya to whoever claimed them in Islam. Two men came and each of them claimed a woman's child. Umar ibn al-Khattab summoned a person who scrutinized features and he looked at them. The scrutinizer said, "They both share in him." Umar ibn al-Khattab hit him with a whip. Then he summoned the woman, and said, "Tell me your tale." She said, "It was this one (indicating one of the two men) who used to come to me while I was with my people's camels. He did not leave me until he thought and I thought that I was pregnant. Then he left me, and blood flowed from me, and this other one took his place. I do not know from which of them the child is." The scrutinizer said, "Allah is greater." Umar said to the child, "Go to whichever of them you wish."
وَحَدَّثَنِي مَالِكٌ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ سُلَيْمَانَ بْنِ يَسَارٍ، أَنَّ عُمَرَ بْنَ الْخَطَّابِ، كَانَ يُلِيطُ أَوْلاَدَ الْجَاهِلِيَّةِ بِمَنِ ادَّعَاهُمْ فِي الإِسْلاَمِ فَأَتَى رَجُلاَنِ كِلاَهُمَا يَدَّعِي وَلَدَ امْرَأَةٍ فَدَعَا عُمَرُ بْنُ الْخَطَّابِ قَائِفًا فَنَظَرَ إِلَيْهِمَا فَقَالَ الْقَائِفُ لَقَدِ اشْتَرَكَا فِيهِ فَضَرَبَهُ عُمَرُ بْنُ الْخَطَّابِ بِالدِّرَّةِ ثُمَّ دَعَا الْمَرْأَةَ فَقَالَ أَخْبِرِينِي خَبَرَكِ فَقَالَتْ كَانَ هَذَا - لأَحَدِ الرَّجُلَيْنِ - يَأْتِينِي . وَهِيَ فِي إِبِلٍ لأَهْلِهَا فَلاَ يُفَارِقُهَا حَتَّى يَظُنَّ وَتَظُنَّ أَنَّهُ قَدِ اسْتَمَرَّ بِهَا حَبَلٌ ثُمَّ انْصَرَفَ عَنْهَا فَأُهْرِيقَتْ عَلَيْهِ دِمَاءٌ ثُمَّ خَلَفَ عَلَيْهَا هَذَا - تَعْنِي الآخَرَ - فَلاَ أَدْرِي مِنْ أَيِّهِمَا هُوَ قَالَ فَكَبَّرَ الْقَائِفُ فَقَالَ عُمَرُ لِلْغُلاَمِ وَالِ أَيَّهُمَا شِئْتَ .