Sahih al-Bukhari 1916
صحيح البخاري#1916SahihNarrated `Adi bin Hatim:When the above verses were revealed: 'Until the white thread appears to you, distinct from the black thread,' I took two (hair) strings, one black and the other white, and kept them under my pillow and went on looking at them throughout the night but could not make anything out of it. So, the next morning I went to Allah's Messenger (ﷺ) and told him the whole story. He explained to me, "That verse means the darkness of the night and the whiteness of the dawn
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: 30:26