R’ Akiva said to them: Do you not agree with me regarding one who placed his eruv in a cave, that he has no more than two thousand cubits? They answered him: ‘‘When is this so? Only when there are no inhabitants in it; but if it had inhabitants in it, he may traverse its entirety and beyond it for two thousand cubits.’’ Thus it follows that its interior is more lenient than its roof. And concerning the surveyor, about whom they said, ‘‘We give him two thou-sand cubits,’’ even if his measurement ended in the middle of a cave [it is so].

One who lives together with a gentile in a [single] courtyard, or with one who does not accept [the laws of] eruv, that person places a restriction upon him — [these are] the words of R’ Meir. R’ Eliezer ben Yaakov says: He never restricts, unless there are two Jews restricting each other.