Sahih al-Bukhari 2111
صحيح البخاري#2111SahihNarrated `Abdullah bin `Umar:Allah's Messenger (ﷺ) said, "Both the buyer and the seller have the option of canceling or confirming a bargain unless they separate, or the sale is optional." (See Hadith No)
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: 34:64