[43a - 28 lines; 43b - 10 lines]
1)[line 8]אינה פנויהEINAH PENUYAH- it is not free, it is in use
2)[line 8]מתנת בית חורוןMATNAS BEIS CHORON - The Mishnah (Nedarim 48a) relates an incident that occurred in Beis Choron where a person (the Madir, whom we will call "Reuven" for convenience) had made a vow prohibiting his father (the Mudar, or "Yakov") from benefiting from him. When Reuven married off his son, he wanted Yakov to join the celebration. For this purpose, he gave to an acquaintance as a gift the courtyard where the wedding would be held, as well as the entire meal, but he specified that he was giving it to him only so that Yakov could come to the ceremony. The acquaintance stated that if the courtyard and the meal were truly his, he was making them Hekdesh to the Beis ha'Mikdash. Reuven objected, saying that they were given to him only for the express purpose of letting Yakov participate in the celebration. The Chachamim ruled that Yakov was still forbidden to benefit from the courtyard and the meal, because it still belonged to Reuven.
Rebbi Yosi forbids the Mudar in our Gemara from benefiting from the Madir (a) because he suspects that at times the person will not really be Mafkir his possessions (make them ownerless), as in the incident in Beis Choron (RAN), or (b) because it does not resemble Hefker, but it is as if he gave it to him directly, similar to what transpired in Beis Choron (TOSFOS DH Ela).