Nedarim, Chapter 4, Mishnah 8. This mishnah is a direct continuation of the previous one, where we learned how someone bound by a vow that forbids him from benefiting from a particular person can nevertheless receive benefit from him indirectly, by way of a third party. Our mishnah takes up a case in which that indirect route is not available: what does he do when there is no third party at hand?
A reminder from the previous mishnah:
Two men were traveling together on the road, and one of them is forbidden to benefit from the other. Reuven is forbidden to benefit from Shimon, and Reuven has nothing to eat. When a third person, Levi, is present with them, Shimon may give the food to Levi as a gift, and Reuven is permitted to receive it from Levi.
The case in our mishnah - when there is no third party:
What is the ruling when there is no other person with them, but only the two of them? The mishnah lays out a sequence of steps:
Shimon places the food on a ledge or on a fence.
He declares about it: "hefker l'chol mi sherotzeh" - ownerless, for whoever wants it.
Reuven comes, takes the food, and eats it.
This leniency is granted because of the difficult circumstances in which Reuven finds himself, and as long as Shimon is not handing him the food directly from hand to hand.
The mishnah, however, closes with a dissenting opinion: Rabbi Yosi forbids it, because he views this as receiving benefit too directly.
In summary: The mishnah teaches that when there is no third party through whom the food can be transferred, one may make use of hefker - placing the food on a ledge or on a fence and declaring it ownerless for anyone, provided that there is no direct giving. And Rabbi Yosi disagrees and forbids it, since in his view this still amounts to benefit that is too direct.