Anas said, "While the Prophet, may Allah bless him and grant himpeace, was with one of his wives, a man passed by and the Prophet, mayAllah bless him and grant him peace, called him and said, 'So-and-so, thisis my wife so-and-so.' The man said, 'Whoever I might suspect, I wouldnot suspect you!' The Prophet said, 'Shaytan flows in the son of Adam likeblood flows.'"
English reference: Book 55, Hadith 1288
Arabic reference: Book 1, Hadith 1288