The Book of Prayers (Kitab Al-Salat)

Muslim :: Book 4 : Hadith 1665

Abu Huraira reported Allah's Apostle (may peace be upon him) as saying: He who prayed on the Lailat-ul-Qadr (the Majestic Night) knowing that it is (the same night). I (believe) that he (the Holy Prophet also) said: (He who does) it with faith and seeking reward (from Allah), his sins would be forgiven.