It was narrated from Ibn 'Umar that:
a man frorn the desert people came to the Prophet and said: "O Messenger of Allah, my wife has given birth on my bed to a black boy, and there are no black people among my family." He said: "Do you have camels?" He said: "Yes." He said: "What color are they?" He said: "Red." He said: are there any black ones among them?" He said, "No." He said: "Are there any grey ones among them?" He said- "Yes." He said "How is that?" He said: "Perhaps it is hereditary." He said: "Perhaps (the color of) this son of yours is also hereditary." (FR)
English reference (FR): Vol. 3, Book 9, Hadith 2003 (FR)
Arabic reference (FR): Book 9, Hadith 2081 (FR)