Sahih Muslim 2962
صحيح مسلم#2962SahihAbdullah b. Shaqiq reported that 'Uthman (Allah be pleased with him) used to forbid Tamattu', whereas 'Ali (Allah be pleased with him) ordered to do it. 'Uthman said a word to 'Ali, but 'Ali said:You know that we used to perform Tamattu' with the Messenger of Allah (ﷺ), whereupon he said: It is right, but we entertained fear
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: 15:171