Sahih al-Bukhari 1030
صحيح البخاري#1030SahihThe narrator Anas added that the Prophet (ﷺ) raised his hands (during the invocation) to such an extent that the whiteness of his armpits was visible
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 15:25