Umar bin Habib narrated to me from a man of Banu Atwarah, and sometimes Sufyan said: from a man of Banu Kinanah, (that he was asked): Are you from Banu so-and-so? I said: No, but they nursed me. He said: I heard Umar (may Allah be pleased with him) saying: "Milk passes on resemblance to him (the child)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرضاع / 15679
Shu'ayb bin Khalid al-Khath'ami narrates from Abdullah bin Umar (may Allah be pleased with them both): Milk passes on resemblance to him (the child).
Abdullah bin al-Walid al-Adani narrated it from al-Thawri with this chain, (saying): I sat with Abdullah bin Umar (may Allah be pleased with them both), and he said: Are they your children? I heard Umar bin al-Khattab (may Allah be pleased with him) say: Nursing passes on resemblance to him (the child).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرضاع / 15680
It is narrated from Ziyad al-Sahmi (may Allah have mercy on him) that the Messenger of Allah (peace and blessings be upon him) forbade having foolish women nurse (children), for milk passes on resemblance. This is mursal.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الرضاع / 15682