Sahih al-Bukhari 245
صحيح البخاري#245SahihNarrated Hudhaifa:Whenever the Prophet (ﷺ) got up at night, he used to clean his mouth with Siwak
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: 4:111