Musnad Ahmad 30:146

Sufyan narrated to us, from al-Zuhri, from Sa’id, from Abu Hurayrah: A man from Banu Fazarah came to the Prophet, peace and blessings of Allah be upon him, and said: "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." He said: "Are there any ashen-colored ones among them?" He said: "Indeed, there are ashen-colored ones among them." He said: "From where did it get that?" He said: "Perhaps it was an ancestral trait that drew it out." He said: "And this [boy], perhaps it was an ancestral trait that drew it out."