"The two parties to a transaction have the choicer so long as they have not separated, unless they reach an agreement before parting, and it is not permissible to hasten to leave for fear that the other party may change his mind." (Using translation from Nasāʾī 4483)
أَنَّ النَّبِيَّ ﷺ قَالَ الْبَائِعُ وَالْمُبْتَاعُ بِالْخِيَارِ حَتَّى يَتَفَرَّقَا إِلَّا أَنْ يَكُونَ سَفْقَةَ خِيَارٍ وَلَا يَحِلُّ لَهُ أَنْ يُفَارِقَهُ خَشْيَةَ أَنْ يَسْتَقِيلَهُ