Sunan an-Nasa'i, Volume 5, Book 44, Hadith 4481 (DarusSalam) ⓘ

It was narrated from Ibn Al-Had, from 'Abdullah bin Dinar, from 'Abdullah bin 'Umar, that he heard the Messenger of Allah say: "When two people meet to engage in trade, the transaction between them is not binding until they separate, unless they have chosen to conclude the transaction."

أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ عَبْدِ الْحَكَمِ، عَنْ شُعَيْبٍ، عَنِ اللَّيْثِ، عَنِ ابْنِ الْهَادِ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّهُ سَمِعَ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏ "‏ كُلُّ بَيِّعَيْنِ فَلاَ بَيْعَ بَيْنَهُمَا حَتَّى يَتَفَرَّقَا إِلاَّ بَيْعَ الْخِيَارِ ‏" ‏ ‏.‏