ENOfficial
It was narrated from 'Amr bin Shu'aib, from his father , form his grandfather, that the Prophet (ﷺ) said: "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."
Source: sunnah.com
Other translations
Arabic
أَخْبَرَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، قَالَ أَنْبَأَنَا اللَّيْثُ، عَنِ ابْنِ عَجْلاَنَ، عَنْ عَمْرِو بْنِ شُعَيْبٍ، عَنْ أَبِيهِ، عَنْ جَدِّهِ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " الْمُتَبَايِعَانِ بِالْخِيَارِ مَا لَمْ يَتَفَرَّقَا إِلاَّ أَنْ يَكُونَ صَفْقَةَ خِيَارٍ وَلاَ يَحِلُّ لَهُ أَنْ يُفَارِقَ صَاحِبَهُ خَشْيَةَ أَنْ يَسْتَقِيلَهُ " .
sunnah.com