Sahih Muslim 1616
صحيح مسلم#1616SahihAbdullah b. Dinar reported on the authority of Ibn 'Umar that the Messenger of Allah (ﷺ) used to observe prayer on his ride (no matter) in which direction it had its face turned. 'Abdullah b. Dinar said that Ibn 'Umar used to do like that
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: 6:47