Sahih al-Bukhari 389
صحيح البخاري#389SahihNarrated Hudhaifa that he saw a person bowing and prostrating imperfectly. When he finished his Salat, Hudhaifa told him that he had not offered Salat. The subnarrator added, "I think that Hudhaifa also said:Were you to die you would die on a "Sunna" (legal way) other than that of Muhammad (ﷺ)
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: 8:41