Musnad Abu Ya'la al-Mawsili 111:20

Abu Ya'la informed us, he said: Muhammad ibn Abi Bakr al-Muqaddami narrated to us, he said: Mu'adh ibn Hisham narrated to us, from his father, from Qatadah, from Anas, from Abu Hurayrah, from the Prophet, may Allah bless him and grant him peace, who said: "Whoever stands (in prayer) during the Night of Decree out of faith and seeking reward, his past sins will be forgiven."