Musnad Ahmad 30:2175

Muhammad ibn Mus'ab narrated to us, Malik ibn Anas narrated to us, from al-Zuhri, from Sa'id ibn al-Musayyib, from Abu Hurayrah, that a man came to the Prophet, may Allah bless him and grant him peace, and said: "O Messenger of Allah, my wife has given birth to a black boy." He said: "Do you have any camels?" He said: "Yes." He said: "What are their colors?" He said: "Red." The Prophet, may Allah bless him and grant him peace, said: "Is it not that perhaps one of them gives birth to a grey camel?" He said: "O Messenger of Allah, yes." He said: "From where do you think that comes?" He said: "I think it is an ancestral trait that has pulled it." The Prophet, may Allah bless him and grant him peace, said: "And this, it is an ancestral trait that has pulled him."