[PAULUS libro tertio ad edictum. ] §2.14.23.prFideiussoris autem conuentio nihil proderit reo, quia nihil eius interest a debitore pecuniam non peti. immo nec confideiussoribus proderit.
[PAULUS, On the Edict, book 3] However, an agreement made by a surety will be of no benefit to the principal debtor, because it is of no concern to him that money should not be demanded from the debtor; indeed, it will not even benefit co-sureties.
§2.14.23.1Neque enim quoquo modo cuiusque interest, cum alii conuentio facta prodest, sed tunc demum, cum per eum, cui exceptio datur, principaliter ei qui pactus est proficiat: sicut in reo promittendi et his qui pro reo obligati sunt.
For it is not just any kind of interest on the part of any person that makes an agreement made with another of benefit to him, but only then when, through the person to whom the exception is given, it primarily benefits the party who made the agreement: as in the case of the principal debtor and those who are bound on his behalf.