Sahih Muslim | Book 18 | Chapter 6

Narrated by 'Aisha
'Aisha reported Allah's Messenger (may peace be upon him) as saying: He who innovates things in our affairs for which there is no valid (reason) (commits sin) and these are to be rejected.

Narrated by Sa'd b. Ibrahim
Sa'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: 'Aisha informed me that Allah's Messenger (may peace be upon him) said: He who did any act for which there is no sanction from our behalf, that is to be rejected.