كتاب البيوع
Read the English translation first, with the original Arabic directly underneath.
Narrated Ibn `Umar:
The Prophet (ﷺ) said, "The buyer and the seller have the option to cancel or confirm the bargain before they separate from each other or if the sale is optional." Nafi` said, "Ibn `Umar used to separate quickly from the seller if he had bought a thing which he liked."
إِنَّ الْمُتَبَايِعَيْنِ بِالْخِيَارِ فِي بَيْعِهِمَا، مَا لَمْ يَتَفَرَّقَا، أَوْ يَكُونُ الْبَيْعُ خِيَارًا