These 2 words are non English. The Punya is what one gets when he or she does good deed and PAAP is something that one gets when one does bad deed . In every religion the concept is there of the good and the bad deed . Even when one talks to children and Santa , the question is are you a good boy or good girl and then Santa will give you Gifts if you are good. This is in this mortal life . All the Abrahamic religions, there is a concept of Afterlife and concept of hell and heaven. So if one has done MORE Punya - good deeds, then one gets to go to heaven. If one has done MORE bad deeds ,then one goes to hell. IN Hindu or Vaidic religion the concepts are different. So this story is related to PUNYA and PAAP .
Ekanath was a great saint and he was fully devoted to the God . One daya man approached him in his house . Ekanath asked him as to why he came to see him. The man answered that he has some incurable disease and he was told that Ekanath was great and he has accumulated lots of Punya and so if he will give his ONE DAY worth of Punya , he will be cured . Ekanath told him that I don't have any Punya as I don't do anything to get Punya , I do it for the love of God. (one gets Punya -good effects of good deeds - it is still a KARMA and that leads to attachment and rebirth. So only way one gets credit for good deed is by continuing to have attachment to the deeds that one does) But he also told that if he has any PUNYA , he is willing to give not only one day worth but entire life's worth of credit to the man for helping him.
So there re 2 points , one that I made it above. Even if one has good credit, it is credit and that will have reaction and also the attachment and so one will have to be born again and that means this type of thinking will give rise to continuation of cycle of Birth and Death . Secondly Ekanath was willing to give credit of good deeds done in his entire life . We are not willing tom part with few dollars forget about the Punya or credits for our good deeds that we have so that we can enjoy in Heaven!!