(Gemara) Question #1: Granted, Shimon may not lend to Reuven, for this benefits him. Why can't Reuven lend to Shimon?

Question #2: Granted, we could say that Reuven may not lend money to Shimon, lest this benefit Reuven (if Shimon will repay better coins), and Reuven may not buy from him (an item in great demand), but why can't Reuven lend objects to Shimon? (The same object is returned!)

Answer #1 (R. Yosi bar Chanina): The case is, Shimon is also Mudar Hana'ah from Reuven.

Answer #2 (Abaye): Chachamim decreed that he may not lend objects, lest he come to borrow.

This also explains the other cases (why Reuven may not lend money to Shimon).

(Mishnah): Reuven asked to borrow Shimon's cow. Shimon said that it is not available. Reuven vowed 'I will never plow my field with it':

If Reuven himself normally plows, he may not plow his field with it, but other people may plow Reuven's field with it;

If Reuven does not normally plow, no one may plow Reuven's field with it.

If Reuven was Mudar Hana'ah from Shimon, and Reuven has nothing to eat, Shimon may go to a grocer and say 'Reuven is Mudar Hana'ah from me. What will I do?'

The grocer supplies Reuven, and Shimon pays for it.

If Reuven needed to build a house or a fence or to harvest his field, Shimon may go to workers and say 'Reuven is Mudar Hana'ah from me. What will I do?'

They do the work Reuven needs, and Shimon pays for it.

If Reuven and Shimon were walking on the road, and Reuven has nothing to eat, Shimon may give a gift of food to a third party, who then gives it to Reuven;

If no one else is around, Shimon leaves the food on a rock or on the fence and declares it Hefker (ownerless). Reuven may then take it;

R. Yosi forbids this.

(Gemara - R. Yochanan) Question: Why does R. Yosi forbid?

Answer #1 (R. Yochanan): R. Yosi holds that Hefker is like a gift.

Just like one may retract from a gift until the recipient gets it, one may retract from Hefker until someone takes it. (It is as if Reuven receives it from Shimon.)

Question (R. Aba - Beraisa): Reuven may take it;

R. Yosi forbids.

R. Yosi: It is forbidden only if the vow preceded the Hefker. If not, it is permitted.

If Hefker does not take effect until someone takes it, it should be forbidden in both cases!

Answer (R. Aba): Anyone who vows does not intend to forbid what he already declared Hefker.

Version #1 - Objection (Rava - Beraisa): Levi (feared lest he die from his illness. He) wrote a document giving part of his property to Yehudah, and a second document giving all of his property to Yosef. (Levi recovered and wants to retract.) Yehudah acquired his gift. (Since Levi did not give all his property, it is like a healthy person's gift, and he cannot retract). Yosef did not acquire his gift.

(If one who vows does not intend to forbid what he declared Hefker, we should also say that one who gives does not intend to give what he already gave.) If so, the latter gift is only for the remaining property.

We should view the two gifts together, and say that Levi gave away all his property, and he should be allowed to retract from both of them!

Version #2 - Objection (Rava - Beraisa): Levi wrote a document giving part of his property to one of his slaves, and a second document giving all of his property to a different slave. The first slave does not acquire (anything, not even freedom, because the document left property for his master. Perhaps this refers to the slave.) The second slave acquires all the property.

(If one does not intend for what he made Hefker... also here... the latter gift is only for the remaining property.) If so, also the latter slave should not acquire anything! (end of Version #2)

Answer #2 (to Question (g) - Rava): R. Yosi decrees due to what occurred in Beis Choron. (Someone gave a 'gift' to evade the Isur of a Mudar Hana'ah, but it became clear that he did not truly intend that it is a gift. Also, here, perhaps he does not truly make it Hefker!)