"Nafi dictated to me, from Ibn 'Umar who said: The Messenger of Allah said: 'the two parties to a transaction both have the choice so long as they have not separated, unless they have both chosen to conclude the transaction. If they have both chosen to conclude the transaction, then the transactions binding." (Sahih ) (Using translation from Nasāʾī 4468)
قَالَ رَسُولُ اللهِ ﷺ «إِذَا تَبَايَعَ الْمُبْتَاعَانِ فَكُلُّ وَاحِدٍ مِنْهُمَا بِالْخِيَارِ مِنْ بَيْعِهِ مَا لَمْ يَتَفَرَّقَا أَوْ يَكُونَ بَيْعُهُمَا عَنْ خِيَارٍ فَإِنْ كَانَ عَنْ خِيَارِ فَقَدْ وَجَبَ الْبَيْعُ»