Abu Hurairah narrated that:The Messenger of Allah [SAW] said: "Whoever stands (in the voluntary night prayer of) Ramadan out of faith and in the hope of reward, his previous sins will be forgiven. And whoever spends the night of Lailat Al-Qadr in prayer out of faith and in the hope of reward, his previous sins will be forgiven

English translation · Sunan an-Nasa'i