Sunan an-Nasa'i, Volume 5, Book 44, Hadith 4483 (DarusSalam) ⓘ
It was narrated from Yazid bin 'Abdullah, from 'Abdullah bin dinar, from ibn '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 الرَّبِيعُ بْنُ سُلَيْمَانَ بْنِ دَاوُدَ، قَالَ حَدَّثَنَا إِسْحَاقُ بْنُ بَكْرٍ، قَالَ حَدَّثَنَا أَبِي، عَنْ يَزِيدَ بْنِ عَبْدِ اللَّهِ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنِ ابْنِ عُمَرَ، أَنَّهُ سَمِعَ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ " كُلُّ بَيِّعَيْنِ لاَ بَيْعَ بَيْنَهُمَا حَتَّى يَتَفَرَّقَا إِلاَّ بَيْعَ الْخِيَارِ " .
also referenced under: Hadith 4478 (Reference) & Book 44, Hadith 30 (In-Book)