Sahih Bukhari Volume 009, Book 089, Hadith Number 283.
Narrated By 'Ali bin Husain : Safiya bint (daughter of) Huyai came to the Prophet (in the mosque), and when she returned (home), the Prophet accompanied her. It happened that two men from the Ansar passed by them and the Prophet called them saying, "She is Safiya!" those two men said, "Subhan Allah!" The Prophet said, "Satan circulates in the human body as blood does."