the Messenger of Allah said: "When two people meet to engage in trade, the transaction between them is not binding until they separate, unless they have chosen to concluded the transaction.
قَالَ رَسُولُ اللَّهِ ﷺ كُلُّ بَيِّعَيْنِ لاَ بَيْعَ بَيْنَهُمَا حَتَّى يَتَفَرَّقَا إِلاَّ بَيْعَ الْخِيَارِ