Sahih al-Bukhari 1255
صحيح البخاري#1255SahihNarrated Um 'Atiyya:Allah's Messenger (ﷺ) , concerning his (dead) daughter's bath, said, "Start with the right side, and the parts which are washed in ablution
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: 23:17