[ULPIANUS libro quadragensimo tertio ad Sabinum. ] §12.7.1.prEst et haec species condictionis, si quis sine causa promiserit uel si soluerit quis indebitum.
[ULPIAN, in his forty-third book On Sabinus.] There is also this species of condictio: if someone has promised without cause, or if someone has paid what was not due.
qui autem promisit sine causa, condicere quantitatem non potest quam non dedit, sed ipsam obligationem.
However, he who has promised without cause cannot claim by condictio the amount which he has not given, but the obligation itself.
§12.7.1.1Sed et si ob causam promisit, causa tamen secuta non est, dicendum est condictionem locum habere.
But also, if he promised for a cause, yet the cause did not follow, it must be said that there is ground for a condictio.
§12.7.1.2Siue ab initio sine causa promissum est, siue fuit causa promittendi quae finita est uel secuta non est, dicendum est condictioni locum fore.
Whether the promise was made without cause from the beginning, or there was a cause for promising which has ended or did not follow, it must be said that there will be ground for a condictio.
§12.7.1.3Constat id demum posse condici alicui, quod uel non ex iusta causa ad eum peruenit uel redit ad non iustam causam.
It is established that only that can be claimed by condictio from someone, which has either come to him not from a just cause, or has returned to an unjust cause.