פירוש על עירובין 7:10

בכל מערבין – the joining of borders/תחומין , whereas, if were the joining of courtyards, we don’t made an Eruv other than with [a loaf of] bread. But however, that Rabbi Eliezer stated here that we make an Eruv with everything includes joining of courtyards with a half-a-loaf of bread and we don’t need a complete loaf, but Rabbi Yehoshua disputes him and states that specifically, an Eruv is a complete loaf. And the Halakha is according to Rabbi Yehoshua.

Introduction In today’s mishnah Rabbi Eliezer and Rabbi Joshua disagree over whether one can set up an eruv with a broken loaf of bread.

אין מערבין בה – and the reason is because of enmity/hostility that the members of the courtyard come to a dispute to state: “I gave a full loaf, and he [only] gave one-half/part of [a loaf].”

They may set up an eruv or a shittuf with all kinds [of food] except for water or salt, the words of Rabbi Eliezer. Rabbi Joshua says: a whole loaf of bread is a valid eruv. Even a baking of one se’ah, if it is a broken loaf, may not be used for eruv while a loaf of the size of an issar, provided it is whole, may be used for eruv. The first line of this mishnah was already taught above in mishnah 3:1, but the context there was border eruvin (eruvei techumin), while here it is courtyard eruvin and alley partnerships (shittufim). Everyone agrees that all types of food except salt and water may be used to set up an eruv. The disagreement in our mishnah is about whether a broken loaf of bread may be used. According to Rabbi Eliezer even a broken loaf is valid. Rabbi Joshua disagrees and holds that only a full loaf is valid. Even if it contains a large amount of dough, even a full seah, if it is broken it is not valid. However, if it is a complete loaf, even if it small, it can count towards one’s eruv. According to the Rambam, a full loaf can constitute an eruv even if it doesn’t meet the minimum requirements listed above in mishnah eight. However, according to Rashi, the small loaf counts towards the eruv, but doesn’t count as the whole eruv unless the minimum requirements are met.

ככר מאיסר והוא שלם מערבין בו – they place it in the Eruv with the rest of the loaves of the members of the courtyard, as long as there will be among all of them the equivalent of a dried fig for each and every one. But Maimonides explained (see Hilkhot Eruvin, Chapter 1, Halakha 8), that a full loaf [of bread] the size of an Issar’s worth (i.e., 8 pennies), we make an Eruv with it alone for all the members of the courtyard and it does not require a [specific] quantity.