10. In dacion en pagol what is delivered by the debtor is merely a thing to be considered as the equivalent of the performance of the obligation . 11. The general rule is that the burden resE on the defendant to prove payment. 12. The rule is that a receipt of payment is the best evidence of the fact of payment. 13. As a rule, payment by an incapacitated person is valid. 14. Payment to a person who is incapacitated to administer his property shall not be valid if he has kept the thing delivered , or insofar as the payment has been beneficial to him. 15. Payment made in good faith to any person in possession of the credit shall release the debtor. 16. As a general rule, payment shall be made in the place of business of the debtor. 1?. The debtor's right to apply payment is mandatory. 13. The debtor's right to apply payment cannot be waived. 19. In case the debtor does not make the application of payment nor the creditor does not also state in which application of payment is made,1en application is made by operation of law. 20. In payment by cession, the debtor is not necessarily in a state of financial difficulty