«من قام ليلة القدر إيمانا واحتسابا غفر له ما تقدم من ذنبه»
The Prophet (peace and blessings be upon him) said:
"Whoever stands (in prayer) on Laylat al-Qadr (the Night of Decree) out of faith and seeking reward, his past sins are forgiven."
Hadith Referenceصحیح الجامع الصغیر / حرف الميم / 6441