[NERATIUS libro septimo membranarum. ] §15.3.18.prQuamuis in eam rem pro seruo meo fideiusseris, quae ita contracta est, ut in rem meam uersaretur (ueluti si, cum seruus frumentum emisset quo familia aleretur, uenditori frumenti fideiusseris), propius est tamen, ut de peculio eo nomine, non de in rem uerso agere possis, ut unius dumtaxat in quoquo contractu de in rem uerso sit actio, qui id ipsum credidit quod in rem domini uersum est.
[NERATIUS, Parchments, book 7] Although you have become surety for my slave in a transaction which was contracted in such a way as to be turned to my account (for example, if, when the slave had bought grain with which the household was to be fed, you became surety to the seller of the grain), yet it is more correct that you can bring an action on that account concerning the peculium, not concerning what was turned to account, so that in any contract the action for what was turned to account belongs only to the single person who trusted [the slave with] that very thing which was turned to the account of the master.