The Prophet ﷺ said, "Whoever stands in prayer during Laylat al-Qadr out of faith and seeking reward, his previous sins will be forgiven."
عن النبي ﷺ قال: من قام ليلة القدر إيمانا واحتسابا غفر له ما تقدم من ذنبه.
Bukhari related it in the Book of Fasting (1901) and Muslim in the Book of the Prayer of Travelers (760), both from the hadith of Hisham, from Yahya bin Abu Kathir, who said, Salama bin Abdul-Rahman narrated to us, from Abu Hurairah, and he mentioned it.There are many hadiths about Laylat al-Qadr recorded in their proper place.