Sahih Muslim 4493
صحيح مسلم#4493SahihSa'd b. Ibrahim reported:I asked Qasim b. Muhammad about a person who had three dwelling houses and he willed away the third part of every one of these houses; he (Qasim b. Muhammad) said: All of them could be combined in one house; and then said: 'A'isha informed me that Allah's Messenger (ﷺ) said: He who did any act for which there is no sanction from our behalf, that is to be rejected
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: 30:24