[TRYPHONINUS libro octauo disputationum. ] §13.7.23.prnec enim amplius a debitore quam debiti summa consequi poterit.
[TRYPHONINUS, Disputations, Book 8] For he cannot recover from the debtor more than the amount of the debt.
sed si stipulatio usurarum fuerat et post quinquennium forte, quam pretium ex re obligata uictus eam emptori restituit, etiam medii temporis usuras a debitore petere potest, quia nihil ei solutum esse, ut auferri non possit, palam factum est: sed si simplum praestitit, doli exceptione repellendus erit ab usurarum petitione, quia habuit usum pecuniae pretii, quod ab emptore acceperat.
But if there had been a stipulation for interest, and if, for example, after five years from when he, having been defeated, restored to the buyer the price [received] from the pledged property, he can also demand from the debtor the interest for the intervening time, because it has become clear that nothing had been paid to him in such a way that it could not be taken away. But if he paid only the simple value, he must be barred from demanding interest by an objection of fraud, because he had the use of the money of the price which he had received from the buyer.