Sahih al-Bukhari 1319
صحيح البخاري#1319SahihNarrated Ash-Shaibani:Ash-Shu`bi said, "I was informed by a man who had seen the Prophet (ﷺ) going to a grave that was separate from the other graves and he aligned the people in rows and said four Takbir." I said, "O Abu `Amr! who narrated (that) to you"? He said, "Ibn `Abbas
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: 23:76