[PAPINIANUS libro nono quaestionum. ] §17.1.53.prQui fide alterius pro alio fideiussit praesente et non recusante, utrosque obligatos habet iure mandati: quod si pro inuito uel ignorante alterutrius mandatum secutus fideiussit, eum solum conuenire potest qui mandauit, non etiam reum promittendi: nec me mouet, quod pecunia fideiussoris reus liberetur: id enim contingit et si meo mandato pro alio soluas.
[PAPINIANUS from the ninth book of Questions] He who has become a surety for another on the mandate of a third party, while that other is present and not objecting, holds both bound under the law of mandate. But if he became a surety following the mandate of one of them while the other was unwilling or ignorant, he can sue only the one who gave the mandate, and not also the principal debtor; nor does it move me that the debtor is released by the money of the surety, for this happens even if you pay for another on my mandate.