[PAULUS libro trigensimo tertio ad edictum. ] §18.5.3.prEmptio et uenditio sicut consensu contrahitur, ita contrario consensu resoluitur, antequam fuerit res secuta: ideoque quaesitum est, si emptor fideiussorem acceperit uel uenditor stipulatus fuerit, an nuda uoluntate resoluatur obligatio.
[PAULUS, Book 33 on the Edict.] Just as purchase and sale is contracted by consent, so is it dissolved by contrary consent, before performance has followed: and therefore the question has been raised whether, if the buyer has accepted a guarantor or the seller has made a stipulation, the obligation is dissolved by mere will.
Iulianus scripsit ex empto quidem agi non posse, quia bonae fidei iudicio exceptiones pacti insunt: an autem fideiussori utilis sit exceptio, uidendum: et puto liberato reo et fideiussorem liberari.
Julian wrote that an action on the purchase indeed cannot be brought, because defenses based on an agreement are inherent in a good-faith action: but it must be considered whether the defense is available to the guarantor: and I think that once the principal debtor is released, the guarantor is also released.
item uenditorem ex stipulatu agentem exceptione summoueri oportet, idemque iuris esse, si emptor quoque rem in stipulationem deduxerit.
Likewise, the seller suing on the stipulation ought to be barred by the defense, and the same rule of law applies if the buyer also has brought the matter into a stipulation.