Jami` at-Tirmidhi 683
جامع الترمذي#683SahihAbu Hurairah narrated that :the Messenger of Allah said: "Whoever fasts Ramadan and stands (in the night prayer) for it out of faith and seeking a reward (from Allah), he will be forgiven what preceded of his sins. Whoever stands (in the night prayer) on the Night of Al-Qadr out of faith and seeking a reward (from Allah), he will be forgiven what preceded of his sins
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan
Zubair Ali ZaiIsnaad Hasan
In-book reference: 8:2