Sunan an-Nasa'i 4474

أَخْبَرَنَا عَلِيُّ بْنُ حُجْرٍ، قَالَ حَدَّثَنَا هُشَيْمٌ، عَنْ يَحْيَى بْنِ سَعِيدٍ، قَالَ حَدَّثَنَا نَافِعٌ، عَنِ ابْنِ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ الْمُتَبَايِعَانِ لاَ بَيْعَ بَيْنَهُمَا حَتَّى يَتَفَرَّقَا إِلاَّ بَيْعَ الْخِيَارِ ‏"‏ ‏.‏

It was narrated from Yahya bin Sa 'eed , who said:"Nafi narrated to us from Ibn 'Umar, who said: 'The Messenger of Allah said: There is no transaction between the two parties until they separate, unless they have chosen to conclude the transaction."" (Sahih)

Reference

Sunan an-Nasa'i 4474

In-book

Book 44, Hadith 26