Abdullah bin Umar reported,

I sold a property of mine in the Valley to the Commander of the Faithful, Uthman bin Affan, in exchange for a property of his at Khaybar. When we had concluded the sale, I turned on my heels and hurried out of his house, fearing that he might revoke the deal. The custom was that the two parties to a sale retained the option to cancel it as long as they had not parted from one another.Abdullah said, "Once my sale and his became binding, I realized that I had gotten the better of him, since I had moved him to the land of Thamud, three nights' journey away, while he had moved me only to Medina, three nights' journey away."

Bukhari 2116

Sahih

قال أبو عبد الله وقال الليث حدثني عبد الرحمن بن خالد عن ابن شهاب عن سالم بن عبد الله

عن عبد الله بن عمر رضي الله عنهما قال

بعت من أمير المؤمنين عثمان بن عفان مالا بالوادي بمال له بخيبر فلما تبايعنا رجعت على عقبي حتى خرجت من بيته خشية أن يرادني البيع وكانت السنة أن المتبايعين بالخيار حتى يتفرقا قال عبد الله فلما وجب بيعي وبيعه رأيت أني قد غبنته بأني سقته إلى أرض ثمود بثلاث ليال وساقني إلى المدينة بثلاث ليال

البخاري 2116صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Bukhari
Book
Sales
Chapter
If someone buys something and gives it as a gift immediately before they separate and the seller does not object to the buyer, or if he buys a slave and frees him
Numbering
Darussalam 2116
Bukhari 2116