Sahih Muslim 2964
صحيح مسلم#2964SahihSa'id b. al-Musayyab reported that 'Ali and 'Uthman (Allah be pleased with them) met at 'Usfan; and Uthman used to forbid (people) from performing Tamattu' and 'Umra (during the period of Hajj), whereupon 'Ali said:What is your opinion about a matter which the Messenger of Allah (ﷺ) did but you forbid it? Thereupon Uthman said: You leave us alone, whereupon he ('Ali) said: I cannot leave you alone. When 'Ali saw this, he put on Ihram for both of them together (both for Hajj and 'Umra)
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: 15:173