Sahih Muslim 261
صحيح مسلم#261SahihUbaidullah b. Abu Bakr said:I heard Anas b. Malik saying: The Messenger of Allah (ﷺ) talked about the major sins, or he was asked about the major sins. Upon this he observed: Associating anyone with Allah, killing of a person, disobedience to parents. He (the Prophet further) said: Should I not inform you about the gravest of the major sins, and (in this connection) observed: False utterance or false testimony. Shu'ba said. It was most probably" false testimony
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: 1:167