[PAULUS libro tertio ad Plautium. ] §2.14.32.prQuod dictum est, si cum reo pactum sit, ut non petatur, fideiussori quoque competere exceptionem: propter rei personam placuit, ne mandati iudicio conueniatur.
[PAULUS, On Plautius, book 3] The rule that if an agreement has been made with the principal debtor that he not be sued, the defense is also available to the guarantor, was established for the sake of the person of the principal debtor, so that he may not be sued in an action on mandate.
igitur si mandati actio nulla sit, forte si donandi animo fideiusserit, dicendum est non prodesse exceptionem fideiussori.
Therefore, if there is no action on mandate, for instance if he became a guarantor with the intention of making a gift, it must be said that the defense does not benefit the guarantor.