Sahih al-Bukhari 973
صحيح البخاري#973SahihNarrated Ibn `Umar:The Prophet (ﷺ) used to proceed to the Musalla and an 'Anaza used to be carried before him and planted in the Musalla in front of him and he would pray facing it (as a Sutra)
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: 13:22