Sahih al-Bukhari 505
صحيح البخاري#505SahihNarrated Nafi`:`Abdullah bin `Umar said, "Allah's Messenger (ﷺ) entered the Ka`ba along with Usama bin Zaid, Bilal and `Uthman bin Talha Al-Hajabi and closed the door and stayed there for some time. I asked Bilal when he came out, 'What did the Prophet (ﷺ) do?' He replied, 'He offered prayer with one pillar to his left and one to his right and three behind.' In those days the Ka`ba was supported by six pillars." Malik said: "There were two pillars on his (the Prophet's) right side
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: 8:152