It is narrated from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) used to observe i'tikaf in the middle ten days of Ramadan. Then one year he observed i'tikaf until the night of the twenty-first (21st of Ramadan), the morning of which he would come out of i'tikaf. The Messenger of Allah (peace and blessings be upon him) said: "Whoever has observed i'tikaf with me should also observe i'tikaf in the last ten days, for I was shown that (special) night, then I was made to forget it, and I saw myself prostrating in water and mud on its morning." Therefore, seek it in the last ten days and seek it in every odd night. Abu Sa'id (al-Khudri, may Allah be pleased with him) said: That night it rained, and the roof of the mosque was made of palm branches, which started to leak. Abu Sa'id (may Allah be pleased with him) said: My two eyes saw that on the morning of the twenty-first (21st), there were traces of water and mud on the forehead and nose of the Messenger of Allah (peace and blessings be upon him).