Sunan an-Nasai 19228
In-book no 4492أَخْبَرَنِي مُحَمَّدُ بْنُ إِسْمَاعِيلَ بْنِ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا يَزِيدُ، قَالَ أَنْبَأَنَا هَمَّامٌ، عَنْ قَتَادَةَ، عَنِ الْحَسَنِ، عَنْ سَمُرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " الْبَيِّعَانِ بِالْخِيَارِ مَا لَمْ يَتَفَرَّقَا وَيَأْخُذْ أَحَدُهُمَا مَا رَضِيَ مِنْ صَاحِبِهِ أَوْ هَوِيَ " .
It was narrated from Al- Hasan from Samurah, who said: "The Messenger of Allah said;" Two traders have the choice as long as they have not separated, or until they reach a deal that suits both of th4em or that is satisfactory (to both)"