Sahih al-Bukhari 799
صحيح البخاري#799SahihNarrated Rifa`a bin Rafi` Az-Zuraqi:One day we were praying behind the Prophet. When he raised his head from bowing, he said, "Sami`a l-lahu liman hamidah." A man behind him said, "Rabbana wa laka l-hamdu, hamdan kathiran taiyiban mubarakan fihi" (O our Lord! All the praises are for You, many good and blessed praises). When the Prophet completed the prayer, he asked, "Who has said these words?" The man replied, "I." The Prophet said, "I saw over thirty angels competing to write it first." Prophet rose (from bowing) and stood straight till all the vertebrae of his spinal column came to a natural position
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: 10:194