Sahih al-Bukhari 2113
صحيح البخاري#2113SahihNarrated Ibn `Umar:The Prophet (ﷺ) said, "No deal is settled and finalized unless the buyer and the seller separate, except if the deal is optional (whereby the validity of the bargain depends on the stipulations agreed upon)
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: 34:66