Sunan an-Nasa'i #4471 · The Book of Financial Transactions

Sunan an-Nasa'iIt was narrated from Al-Laith from Nafi from Ibn 'Umar who said
Sunan an-Nasa'i · Book 44 · The Book of Financial Transactions
Sunan an-Nasa'i · كتاب 44 · كتاب البيوع والمعاملات
"The Messenger of Allah said: 'The two parties to a transaction both have the choice so long as they have not separated or they have chosen to conclude the transaction.' Or perhaps Nafi said: "Or one of them has said to the other: 'Decide! (Sahih)
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا اللَّيْثُ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏
"‏ الْبَيِّعَانِ بِالْخِيَارِ حَتَّى يَفْتَرِقَا أَوْ يَكُونَ بَيْعَ خِيَارٍ ‏"‏ ‏.‏ وَرُبَّمَا قَالَ نَافِعٌ ‏"‏ أَوْ يَقُولَ أَحَدُهُمَا لِلآخَرِ اخْتَرْ ‏"‏ ‏.‏
Reference : Sunan an-Nasa'i 4471In-book reference : Book 44, Hadith 23