The tractate opens with the mavoi - an alley onto which courtyards open - and the height of the beam at its entrance.
מָבוֹי שֶׁהוּא גָּבוֹהַּ לְמַעְלָה מֵעֶשְׂרִים אַמָּה — יְמַעֵט. רַבִּי יְהוּדָה אוֹמֵר: אֵינוֹ צָרִיךְ.
An alley whose entrance beam is higher than twenty amot - he must lower it.
An alley whose entrance beam is higher than twenty amot - he must lower it. Rabbi Yehudah says: he need not. The Gemara compares the Mishnah of Sukkah, which says "invalid" rather than "lower it," and examines why the wording differs.
Eruvin is a tractate of structures and spaces. Sketch each case before concluding, and bring practical questions to a rabbi.
This lesson is a study framework, not a halachic ruling. Check everything in the sources, and bring practical questions to a rabbi.
Sketch an alley with a beam at its entrance and mark the twenty-amah line.
From the opening, the tractate teaches reading a diagram.
Test yourself before marking the lesson complete.
What if the beam is above twenty amot?
