Sahih al-Bukhari 5261
صحيح البخاري#5261SahihNarrated `Aisha:A man divorced his wife thrice (by expressing his decision to divorce her thrice), then she married another man who also divorced her. The Prophet (ﷺ) was asked if she could legally marry the first husband (or not). The Prophet (ﷺ) replied, "No, she cannot marry the first husband unless the second husband consummates his marriage with her, just as the first husband had done
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: 68:11