De iure libellorum liber singularis
Dig. 50,7,12Idem libro singulari de iure libellorum. Si absenti iniuncta est legatio eamque gratuitam suscepit, potest quis et per alium legationem mittere. 1Qui legationis officio fungitur, licet suum negotium curare non potest, magnus tamen Antoninus permisit ei pupillae nomine et instruere et defendere causam, licet legationi, quam suscepit, nondum renuntiaverit, praecipue cum participem officii ipsius absentem esse dicebat.
The Same, On the Right of Petition. Where anyone is appointed an envoy during his absence, and voluntarily accepts the office, he can send another to discharge its duties in his place. 1Although anyone who performs the duties of an envoy cannot transact his own business, still, the Great Antoninus permitted him to prosecute and defend cases in the name of a female ward; although he had not yet attended to the affairs of the embassy which he had undertaken, and especially when he alleged that the guardian for whom he acted was absent.