[POMPONIUS libro quinto decimo ad Sabinum. ] §12.6.16.prSub condicione debitum per errorem solutum pendente quidem condicione repetitur, condicione autem exsistente repeti non potest.
[POMPONIUS, On Sabinus, Book 15.] A debt due under a condition which has been paid by mistake is recovered while the condition is still pending, but when the condition has been fulfilled, it cannot be recovered.
§12.6.16.1Quod autem sub incerta die debetur, die exsistente non repetitur.
But what is owed under an uncertain day cannot be recovered once that day has arrived.