Sahih al-Bukhari 1952
صحيح البخاري#1952SahihNarrated `Aisha:Allah's Messenger (ﷺ) said, "Whoever died and he ought to have fasted (the missed days of Ramadan) then his guardians must fast on his behalf
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: 30:59