Sahih al-Bukhari 6244
صحيح البخاري#6244SahihNarrated Anas:Whenever Allah's Messenger (ﷺ) greeted somebody, he used to greet him three times, and if he spoke a sentence, he used to repeat it thrice
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: 79:18