Narrated Abu Huraira: Allah's Apostle said, "Whoever establishes the prayers on the night of Qadr out of sincere faith and hoping to attain Allah's rewards (not to show off) then all his past sins will be forgiven."
Hadith ReferenceSahih Bukhari / The Book of Belief (Faith) / Hadith: 35
Hadith Gradingمحدثین:أحاديث صحيح البخاريّ كلّها صحيحة