Sahih al-Bukhari Book 33, Hadith 13
The wives of the Prophet (ﷺ) were with him in the mosque (while he was in I`tikaf) and then they
departed and the Prophet (ﷺ) said to Safiya bint Huyai, "Don't hurry up, for I shall accompany you," (and
her dwelling was in the house of Usama). The Prophet (ﷺ) went out and in the meantime two Ansari men
met him and they looked at the Prophet (ﷺ) and passed by. The Prophet (ﷺ) said to them, "Come here. She is
(my wife) Safiya bint Huyai." They replied, "Subhan Allah, (How dare we think of evil) O Allah's
Apostle! (we never expect anything bad from you)." The Prophet (ﷺ) replied, "Satan circulates in the
human being as blood circulates in the body, and I was afraid lest Satan might insert an evil thought in
your minds."
One of the wives of Allah's Messenger (ﷺ) practiced I`tikaf with him while she ad bleeding in between her periods and she would see red (blood) or yellowish traces, and sometimes we put a tray beneath her when she offered the prayer.
Safiya went to the Prophet (ﷺ) while he was in I`tikaf. When she returned, the Prophet (ﷺ) accompanied her walking. An Ansari man saw him. When the Prophet (ﷺ) noticed him, he called him and said, "Come here. She is Safiya. (Sufyan a sub-narrator perhaps said that the Prophet (ﷺ) had said, "This is Safiya"). And Satan circulates in the body of Adam's offspring as his blood circulates in it." (A sub-narrator asked Sufyan, "Did Safiya visit him at night?" He said, "Of course, at night.")