[PAULUS libro quarto ad Plautium. ] §15.4.5.prSi dominus uel pater pecuniam mutuam accepturus iusserit seruo filioue numerari, nulla quaestio est, quin ipsi condici possit: immo hoc casu de iussu actio non competit.
[PAULUS, On Plautius, book 4] If a master or a father, intending to receive borrowed money, has ordered it to be paid to his slave or son, there is no question that a personal action (condictio) can be brought against him himself; on the contrary, in this case, the action on the order (actio de iussu) does not lie.
§15.4.5.1Si unus ex serui dominis iussit contrahi cum eo, is solus tenebitur: sed si duo iusserunt, cum quouis in solidum agi potest, quia similes sunt duobus mandantibus.
If one of the masters of a slave has ordered a contract to be made with him, he alone shall be liable; but if two have given the order, an action can be brought against either of them for the whole amount (in solidum), because they are similar to two mandators.