Sahih al-Bukhari 42
صحيح البخاري#42SahihNarrated Abu Huraira: Allah's Messenger (ﷺ) said, "If any one of you improves (follows strictly) his Islamic religion then his good deeds will be rewarded ten times to seven hundred times for each good deed and a bad deed will be recorded as it is
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: 2:35