One who slept while on a journey and did not know that it had become dark has two thousand cubits in every direction — [these are] the words of R’ Yochanan ben Nuri. But the Sages say: He has only four cubits. R’ Eliezer says: And he is in their midst. R’ Yehudah says: He may go in any direction he wishes. Yet R’ Yehudah agrees that once he chooses for himself, he cannot retract.

If there were two, some of the cubits of one overlapping the cubits of the other, they may bring [their food] and eat in the middle, provided that one does not carry from his into his friend’s. If there were three and the middle one’s [area] was overlapped by the other two, he is permitted with them, and they are permitted with him; but the outer two are forbidden with each other. Said R’ Shimon: To what is this comparable? To three courtyards which open one into the other and which open into the public domain. If the two made an eruv with the middle one, it is permitted to them, and they are permitted to it; but the two outer ones are forbidden one to another.

One who was traveling as darkness approached, and he knew [of] a tree or a fence, and said, ‘‘My Sabbath dwelling place is beneath it,’’ has said nothing. [If, however, he said,] ‘‘My Sabbath dwelling place is at its trunk,’’ he may walk from his present location to the trunk two thousand cubits, and from the trunk to his house two thousand cubits. Thus, he may go four thousand cubits after dark.

If he does not know, or he is not conversant with the law, and he said, ‘‘My Sabbath dwelling place is at my location,’’ his location acquires two thousand cubits for him in every direction. In a circle — [these are] the words of R’ Chanina ben Antignos. But the Sages say: In a square, like a square board, so that he may gain the corners.