Sahih Muslim 6781
صحيح مسلم#6781SahihAbu Sa'id al-Khudri reported Allah's Messenger (ﷺ) as saying:You would tread the same path as was trodden by those before you inch by inch and step by step so much so that if they had entered into the hole of the lizard, you would follow them in this also. We said: Allah's Messenger, do you mean Jews and Christians (by your words)" those before you"? He said: Who else (than those two religious groups)?
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: 47:7