The Prophet (may Allah's peace and blessings be upon him) tells about the merit of Qiyām al-Layl in the Night of Decree, which lies in the last ten days of Ramadan; that whoever engages in a lot of prayer, supplication, Qur'an recitation, and dhikr in this night, believing in it and its reported merit, seeking Allah's reward by his deed, without show-off or pursuit of reputation among people, his previous sins will be forgiven.