Musnad al-Humaydi

Sayyiduna Abu Sa‘id Khudri (may Allah be pleased with him) narrates: The Noble Prophet (peace and blessings be upon him) observed i‘tikaf in the middle ten days of the month of Ramadan. We also observed i‘tikaf with him. When the morning of the twentieth night came, we began to move our belongings. The Noble Prophet (peace and blessings be upon him) noticed us and said: “Whoever among you wishes to observe i‘tikaf should return to his place of i‘tikaf, for I have been shown this night (i.e., Laylat al-Qadr) in the last ten nights. I saw myself, on the morning of that night, prostrating in water and mud (i.e., in clay).” (The narrator says) It rained that day. The roof of the mosque was made of palm branches, so water collected at the place where the Noble Prophet (peace and blessings be upon him) prayed. I saw the Noble Prophet (peace and blessings be upon him), when he finished the morning prayer, there was a mark of water and mud (i.e., clay) on his blessed forehead and nose.