Sahih Muslim 1576
صحيح مسلم#1576SahihIbn 'Abbas reported:Allah has prescribed the prayer by the tongue of your Apostle (ﷺ) as two rak'ahs for the traveller, four for the resident, and one in danger
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: 6:7