Sahih al-Bukhari 35
صحيح البخاري#35SahihNarrated Abu Huraira: Allah's Messenger (ﷺ) said, "Whoever establishes the prayers on the night of Qadr out of sincere faith and hoping to attain Allah's rewards (not to show off) then all his past sins will be forgiven
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 2:28