(97) باب
Narrated Nafi':
Whenever 'Abdullah entered the Ka'bah, he used to go ahead leaving the door of the Ka'bah behind him. He would proceed on till the remaining distance between him and the opposite wall about three cubits. Then he would off prayer there where the Prophet (ﷺ) had offered Salat, as Bilal informed me. Ibn 'Umar said, "It does not matter for any of us to offer prayers at any place inside the Ka'bah."
Reference: Sahih al-Bukhari 506
In-book reference: Book 8, Hadith 153
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 8, Hadith 484