Sahih al-Bukhari 4155
صحيح البخاري#4155SahihAbdullah bin Abi `Aufa said, "The people (who gave the Pledge of allegiance) under the Tree numbered 1300 and the number of Bani Aslam was 1/8 of the Emigrants
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: 64:199