There is no transaction between two persons entering a transaction until they separate, but only when there is an option to annul it.
Sahih Muslim Book 21, Hadith 56
← Previous Hadith When two persons enter into a transac. tion, each one of them has the right to annul it so long as they are not separated, or their transaction gives one another (as a condition) the right of annulling, and if their transaction, has the right of annulling it the transaction becomes binding. Ibn Abi Umar made this addition that whenever he (Ibn Umar) entered into a transaction with a person with the intention of not breaking it, he walked a while and then returned to him.

Sahih Muslim Book 21, Hadith 55 Next Hadith → Both parties in a business transaction have the right to annul it so long as they have not separated; and if they speak the truth and make everything clear they will be blessed in their transaction; but if they tell a lie and conceal anything the blessing on their transaction will be blotted out.

Sahih Muslim Book 21, Hadith 57