Sahih al-Bukhari 1100
صحيح البخاري#1100SahihNarrated Anas bin Seereen:We went to receive Anas bin Malik when he returned from Sham and met him at a place called 'Ain at-Tamr. I saw him praying riding the donkey, with his face to this direction, i.e. to the left of the Qibla. I said to him, "I have seen you offering the prayer in a direction other than that of the Qibla." He replied, "If I had not seen Allah's Messenger (ﷺ) doing it, I would not have done it
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: 18:20