Sahih Bukhari
Beginning of Creation
Volume: 004 / Book Number: 054 / Hadith Number: 501
Narrated Safiya bint Huyay:
While Allah's Apostle was in Itikaf, I called on him at night and having had a talk with him, I got up to depart. He got up also to accompany me to my dwelling place, which was then in the house of Usama bin Zaid. Two Ansari men passed by, and when they saw the Prophet they hastened away. The Prophet said (to them). "Don't hurry! It is Safiya, the daughter of Huyay (i.e. my wife)." They said, "Glorified be Allah! O Allah's Apostle! (How dare we suspect you?)" He said, "Satan circulates in the human mind as blood circulates in it, and I was afraid that Satan might throw an evil thought (or something) into your hearts."