Sahih Muslim 7546
صحيح مسلم#7546SahihUbaidullah b. 'Abdullah b. 'Utba reported:Ibn Abbas said to me: Do you know-and in the words of Harun (another narrator): Are you aware of-the last Sura which was revealed in the Qur'an as a whole? I said: Yes," When came the help from Allah and the victory" (cx.). Thereupon, he said: You have told the truth. And in the narration of Abu Shaiba (the words are): Do you know the Sura? And he did not mention the words" the last one
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: 56:24