Whoever spends the Night of Qadr standing (in voluntary prayer) out of faith and seeking reward from Allah, his previous sins will be forgiven. [Al-Bukhari]
"من قام ليلة القَدْر إيمَانا واحْتِسَابًا غُفِر له ما تَقدم من ذَنْبِه». [صحيح] - [متفق عليه.]"
