Musnad Abu Ya'la al-Mawsili 155:29

Ishaq ibn Abi Isra'il narrated to us, Sufyan narrated to us, from al-Zuhri, who heard Sa'id ibn al-Musayyib, who heard Abu Hurayrah saying: A man came to the Prophet, may Allah bless him and grant him peace, 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 ones among them." He said: "From where did they get that?" He said: "Perhaps an ancestral trait pulled it out." He said: "And this [boy], perhaps an ancestral trait pulled it out."