One-fifth of Booty to the Cause of Allah (Khumus)

Bukhari :: Book 4 :: Volume 53 :: Hadith 333

Narrated Safiya:

(the wife of the Prophet) That she came to visit Allah's Apostle while he was in Itikaf(i.e. seclusion in the Mosque during the last ten days of Ramadan. When she got up to return, Allah's Apostle got up with her and accompanied her, and when he reached near the gate of the Mosque close to the door (of the house) of Um Salama, the wife of the Prophet, two Ansari men passed by them and greeted Allah's Apostle and then went away. Allah's Apostle addressed them saying, "Don't hurry! (She is my wife)," They said, "Glorified be Allah! O Allah's Apostle (You are far away from any suspicion)," and his saying was hard on them. Allah's Apostle said, "Satan circulates in the mind of a person as blood does (in his body). I was afraid that Satan might put some (evil) thoughts in your minds."