Eruvin, Chapter Two, Mishnah 6. In the previous mishnayos we discussed the size of the area that may be enclosed by partitions when it was not enclosed for the purpose of a dwelling, that is, how large an area may be, and one may still carry within it. Our mishnah opens with this subject, in the name of Rabbi Ilai, who reports three teachings that he heard from Rabbi Eliezer.
The first testimony - the size of the area:
"Shamati meRabbi Eliezer: va'afilu hi k'veis kor" - even if the area that is surrounded by partitions but was not enclosed for human habitation is the size of a beis kor, which is thirty se'ah, fifteen times the size of a beis se'atayim, one may carry within it, as long as it is surrounded by partitions.
The second testimony - relinquishing one's rights in a courtyard:
Rabbi Ilai goes on to report additional teachings that he heard from Rabbi Eliezer, which are not related to the subject of this chapter: "V'chen shamati mehen: anshei chatzer sheshachach echad mehen v'lo eiruv - beiso asur lo mil'hachnis umil'hotzi lo". In order for the residents of a courtyard to be permitted to carry in the courtyard, all the households in the courtyard must join together in an eiruv chatzeiros, for example, through a shared box of matzos. If one of them forgot and did not join in the eiruv, he may not bring anything into his house or take anything out of it.
What case is being discussed here? A person who, on Shabbos itself, after realizing that he had not joined in the eiruv, relinquishes his rights in the courtyard. He says: I remove my ownership in the courtyard, so that those who joined in the eiruv are the only ones who have ownership in it. In such a case Rabbi Ilai teaches in the name of Rabbi Eliezer that one who relinquishes his rights in the courtyard relinquishes his rights in the house itself as well. Therefore he may not bring anything into his house or take anything out of it, for if he were to do so he would reacquire his ownership in the courtyard, and thereby nullify the eiruv for that Shabbos.
Regarding the other residents of the courtyard, however, the mishnah says: "V'lahem mutar" - those people who joined in the eiruv, and in whose favor he relinquished his rights, are permitted to bring things into his house and take things out of it, since according to Rabbi Eliezer relinquishing one's rights in the courtyard includes the house as well.
The third testimony - maror:
Rabbi Ilai also heard from Rabbi Eliezer that the mitzvah of eating maror on Pesach can be fulfilled with a certain type of plant called akravanin.
Concerning these three halachos - the permission to enclose an area even as large as a beis kor, relinquishing one's rights in a courtyard including the house, and akravanin as maror - Rabbi Ilai testifies: "I went around to all of Rabbi Eliezer's students and sought a colleague who had heard the same, and I did not find one." He was the only voice on these matters.
The halachah: The halachah does not follow any of these three opinions:
In a garden and in a karpaf, the area outside the city used for storage, which are not intended for human habitation, one may carry only up to a beis se'atayim.
When a person relinquishes his rights in the courtyard, the relinquishment does not include his house, and therefore the other residents of the courtyard may not carry into his house or out of it.
Akravanin is not a plant with which the mitzvah of maror on Pesach may be fulfilled.