Another one of the rules presented by the Mishna (48b) for reasons of tikkun olam is En nifra’im mi-nehasim meshubadim be-makom she-yesh b’ne horin – that payment will not be taken from “obligated” monies when “free” monies are available.
The idea of “obligated” monies (nehasim meshubadim) as opposed to “free” monies (nehasim b’ne horin) works as follows. When a person borrows money and signs a formal loan agreement, all of his property becomes obligated to secure the loan. Thus, if a person cannot pay back his loan, the lender can collect real estate that the borrower owned at the time of the original loan – even if it has been sold to a third party in the interim. This works because the purchaser had the opportunity when he bought the field to examine liens that existed on the real estate and accepted the risk at that time. Of course, if the field is taken from him in payment of the loan, he will be able to try and collect the value of the field from the seller (although we already know that he is someone who does not have available cash to pay).
The ruling of the Mishna is that nehasim meshubadim will be collected in payment of the debt only if the borrower has no other means of payment. If he has real-estate in his hands – even if it is ziburit (the lowest quality land) – that is what will be used as payment, even though the lender usually should be receiving benonit (middle quality land).
Our Gemara asks whether the protection offered by the sages to the purchaser of land would extend to cases where the borrower gave away that same land as a present. In his Haver ben Hayyim, Rav Hizkiya Feivel Ploit explains the question as follows:
Was the rabbinic enactment to protect nehasim meshubadim from collection made in order to encourage business, so that someone purchasing land should feel secure that the field he is buying will not be taken from him, in which case, it only applies to sales and not to land that is given as a present, or was the enactment made to protect people who have received land from others, in which case it would be applied in all cases.
The Rambam understands the conclusion of the Gemara as applying the enactment in all cases.