Is there a "right of assembly" (khiyar al-majlis) for currency exchange (bay' al-sarf)?

The preponderant opinion is that the option of the session (khiyār al-majlis) is affirmed in currency exchange (sarf), like other sales, due to the generality of the Prophet's (peace be upon him) saying: "The two parties to a sale have the option as long as they have not separated." This is also because it was legislated with consideration for what is most beneficial, and this is present in both currency exchange and forward sales (salam). Others, however, hold the view that the option is not affirmed in these two types of transactions.