Qitzur Shulchan Arukh – 180:16
Prozbul doesn’t help unless the borrower has land. Even if it’s a minimal amount, it’s sufficient. Even if he only has a pot with a whole in the bottom [thus connecting its dirt to the ground], it is sufficient. Even if the borrower has nothing, but the cosigner or someone who owes this borrower money [does], that also helps. And if they also do not have anything, if the lender has a minimal amount of land, he could give rights to it to the borrower, even through another party and not before the borrrwer, and the pruzbol would help.