[PAULUS libro tertio ad edictum. ] §12.2.14.prQuotiens propter rem iuratur, nec parenti nec patrono remittitur iusiurandum: propter rem autem iusiurandum exigitur ueluti de pecunia credita, cum iurat actor sibi dari oportere uel reus se dare non oportere.
[PAULUS, Book III on the Edict.] Whenever an oath is sworn in relation to a property matter, the oath is excused neither for a parent nor for a patron; on the other hand, an oath in relation to a property matter is required, for example, concerning loaned money, when the plaintiff swears that it ought to be given to him, or the defendant that he ought not to give it.
idem est, cum de pecunia constituta iusiurandum exigitur.
The same is true when an oath is required concerning agreed money.