Sahih Muslim 1572
صحيح مسلم#1572SahihA'isha reported:The prayer was prescribed as consisting of two rak'ahs, the prayer in travelling remained the same, but the prayer at the place of residence was completed. (Zuhri said he asked 'Urwa why 'A'isha said prayer in the complete form during journey, and he replied that she interpreted the matter herself as 'Uthman did)
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: 6:3