[PAULUS libro uicensimo ad edictum. ] §3.5.22.prSi quis negotia aliena gerens indebitum exegerit, restituere cogitur: de eo autem, quod indebitum soluit, magis est ut sibi imputare debeat.
[PAULUS, On the Edict, book twenty] If anyone, in managing another's business, has exacted what was not due, he is compelled to restore it; but concerning that which he paid when it was not due, it is more reasonable that he should impute it to himself.