Sahih al-Bukhari Book 33, Hadith 12
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.
I asked Abu Sa`id Al-Khudri, "Did you hear Allah's Messenger (ﷺ) talking about the Night of Qadr?" He replied in the affirmative and said, "Once we were in I`tikaf with Allah's Messenger (ﷺ) in the middle ten days of (Ramadan) and we came out of it in the morning of the twentieth, and Allah's Messenger (ﷺ)delivered a sermon on the 20th (of Ramadan) and said, 'I was informed (of the date) of the Night of Qadr (in my dream) but had forgotten it. So, look for it in the odd nights of the last ten nights of the month of Ramadan. I saw myself prostrating in mud and water on that night (as a sign of the Night of Qadr). So, whoever had been in I`tikaf with Allah's Messenger (ﷺ) should return for it.' The people returned to the mosque (for I`tikaf). There was no trace of clouds in the sky. But all of a sudden a cloud came and it rained. Then the prayer was established (they stood for the prayer) and Allah's Messenger (ﷺ) prostrated in mud and water and I saw mud over the forehead and the nose of the Prophet.
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."