Sahih Muslim 1115
صحيح مسلم#1115SahihIbn Umar reported:When the Messenger of Allah (may peace he upon him) went out on the 'Id day, he ordered to carry a spear-and it was fixed in front of him, and he said prayer towards its (direction), and the people were behind him. And he did it in the journey, and that is the reason why the Amirs carried it
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: 4:277