Sahih Muslim 3240
صحيح مسلم#3240SahihA'isha (Allah be pleased with her) reported:Allah's Messenger may peace be upon him) said to me: Had your people not been unbelievers in the recent past (had they not quite recently accepted Islam), I would have demolished the Ka'ba and would have rebuilt it on the foundation (laid) by Ibrahim; for when the Quraish had built the Ka'ba, they reduced its (area), and I would also have built (a door) in the rear
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 15:444