Sahih al-Bukhari 2117
صحيح البخاري#2117SahihNarrated `Abdullah bin `Umar:A person came to the Prophet (ﷺ) and told him that he was always betrayed in purchasing. The Prophet (ﷺ) told him to say at the time of buying, "No cheating
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: 34:70