Sulayman bin Yasar (may Allah have mercy on him) said: Whenever a child from the time of Jahiliyyah was claimed in Islam, Sayyiduna Umar (may Allah be pleased with him) would attach him to the one who claimed him. Sulayman (may Allah have mercy on him) said: Two men were both claiming a woman's child, so Sayyiduna Umar (may Allah be pleased with him) called a physiognomist. He looked at the two of them and said: Both of them share in him. Sayyiduna Umar (may Allah be pleased with him) struck him with a whip and said to the woman: Tell me the true account. She said: This man used to come to me while I was among my family's camels, until he firmly believed that a pregnancy had become established; then he left me, and then I bled. After that, the other one began to come. I do not know from which of the two he is. At that the physiognomist said Allahu Akbar, and Sayyiduna Umar (may Allah be pleased with him) said: Go with whichever of them you wish.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الدعوى والبينات / 21263