The etiquette of transactions where an honest exchange of goods is blessed

Messenger of Allah ﷺ said, "The seller and the buyer have the right to keep or return goods as long as they have not parted or till they part; and if both the parties spoke the truth and described the defects and qualities (of the goods), then they would be blessed in their transaction, and if they told lies or hid something, then the blessings of their transaction would be lost."  

قَالَ رَسُولُ اللَّهِ ﷺ: «الْبَيِّعَانِ بِالْخِيَارِ مَا لَمْ يَتَفَرَّقَا» أَوْ قَالَ «حَتَّى يَتَفَرَّقَا۔ فَإِنْ صَدَقَا وَبَيَّنَا بُورِكَ لَهُمَا فِي بَيْعِهِمَا وَإِنْ كَتَمَا وَكَذَبَا مُحِقَتْ بَرَكَةُ بَيْعِهِمَا۔»