Sahih al-Bukhari 4704
صحيح البخاري#4704SahihNarrated Abu Huraira:Allah's Messenger (ﷺ) said, "The Um (substance) of the Qur'an is the seven oft-repeated verses (Al-Mathani) and is the Great Qur'an (i.e. Surat-al-Fatiha)
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: 65:226