Ex Plautio libri
Ex libro IV
The Same, On Plautius, Book IV. A party who pays in the name of the heir and with money belonging to the heir, legacies which are not due, cannot himself bring an action for the recovery of what he paid; but if he paid the money of the heir without the knowledge of the latter, then the owner of the money, it is held, can properly bring suit to recover it. The same rules apply to corporeal property of all kinds.
Javolenus, On Plautius, Book IV. When suit is brought for the production of a slave who has been given in pledge, proceedings must be instituted against the creditor, and not against the debtor; for the reason that he who gave the slave in pledge only possesses him by the right of usucaption. In all other respects, however, he who receives property possesses it, and this is true to such an extent that the possession of him who gives property in pledge can also be included.