Chapter: The virtue of Lailat Al-Qadr and the Exhortation to seek it; When it is and the most likely times to seek it
Abu Sa'id al-Khudri (Allah be pleased with him) reported that the Messenger of Allah ( صلی اللہ علیہ وسلم ) devoted (himself to prayer) in the middle (ten nights) of Ramadan. The rest of the hadith is the same except for these words: That he adhered to his place of i'tikaf and his forehead was besmeared with mud and water.
Authentic