GEMARA: The tanna of the mishna opens by speaking of a pit: A person may not dig a pit close to the pit of another, and yet he ends with a reference to a wall: Unless he distances it from the wall of another. Let the tanna teach: Unless he distanced his pit or ditch three handbreadths from the pit of another, just as he begins his statement by referring to a pit. Why does the mishna suddenly mention a wall here?

Abaye said, and some say it was Rav Yehuda who said: We learned that the mishna means: From the wall of his pit. In other words, one should read the mishna as follows: Unless he distanced his pit or ditch three handbreadths from the wall of another’s pit. The neighbor also built his pit close to the border between the two properties, and the mishna is teaching that the one digging a pit must distance it three handbreadths from the wall of the pit of the other.

The Gemara challenges: But even so, let it teach: Unless he distanced his excavations three handbreadths from the pit of another, and one would understand that the term pit is referring to the wall of the other’s pit. The Gemara responds: By using the phrase: From the wall of another, this teaches us incidentally that the wall of a pit must be at least three handbreadths thick, as the wall of the other’s pit occupied the full three handbreadths between the cavity of his pit and the property of his neighbor. The practical difference of this observation is with regard to buying and selling, as it is taught in a baraita: With regard to one who says to another: I am selling you a pit and its walls, the wall of the pit must be at least three handbreadths thick.

§ It was stated: With regard to one who comes to dig any of these excavations or place any of the items listed in the mishna close to the boundary of his field, where his neighbor currently has no pit, Abaye says: He may dig or place them close to the boundary; and Rava says: He may not dig or place them close to the boundary. The Gemara explains: All agree that he may not dig or place them close to a field of his neighbor if that field is designated for digging pits, as he will thereby restrict his neighbor from using his field in the manner it is expected to be used. When they disagree it is with regard to a field that is not designated for digging pits.

The Gemara elaborates: Abaye says: He may dig these excavations or place these items close to the boundary, as the neighbor’s field is not designated for pits, so he is not causing any damage by doing so. Rava says: He may not dig these excavations or place these items close to the boundary, as the neighbor can say to him: Just as you changed your mind and dug a pit, I too might change my mind and dig a pit, and I will no longer be able to dig near my border if you dig your pit close to the boundary.

There are those who say a different version of this discussion: All agree that one may dig these excavations or place these items close to the boundary of a field that is not designated for digging pits. When they disagree it is with regard to a field that is designated for digging pits. Abaye says: One may dig these excavations or place these items close to the boundary; and this is the halakha even according to the opinion of the Rabbis, who say in the mishna (25b): One must distance a tree twenty-five cubits from a cistern, lest the roots of the tree grow and damage a neighbor’s cistern in his field. The difference is that there it is prohibited, as when he plants the tree there is already a cistern. But here, at the time when he digs his cistern, there is as yet no cistern in his neighbor’s field.

And Rava says: One may not dig these excavations or place these items close to the boundary; and this is the halakha even according to the opinion of Rabbi Yosei, who says in that same mishna: This one may dig in his field and that one may plant in his field, i.e., one need not distance his tree for fear of damaging his neighbor’s field through expanding roots. The reason that Rava maintains that his ruling is correct even according to the opinion of Rabbi Yosei is that this matter applies only there, as when he plants the tree, its roots, which might damage the cistern, are not yet present. Consequently, when he plants he does not cause any damage. But here, the neighbor can say to him: Each and every strike of yours with the hoe loosens my earth, and therefore you are already causing damage as you dig your cistern.

The Gemara suggests a proof: We learned in the mishna that a person may not dig a pit close to the pit of another, unless he does so at a distance of three handbreadths from his neighbor’s wall. The Gemara analyzes this statement: Apparently, the reason he may not dig close to the boundary of his neighbor’s field is that there is a pit there, from which it may be inferred that if there is no pit he may dig his pit close to his neighbor’s wall. Granted, according to that second version of the dispute, in which you said: All agree that one may dig these excavations or place these items close to the boundary of a field that is not designated for digging pits, one can explain that the mishna is referring to a field that is not designated for digging pits.

But according to that first version of the dispute, in which you said that they disagree with regard to a field that is not designated for digging pits, there is a difficulty. Granted, this works out well according to the opinion of Abaye, who says that one may dig one’s pit near the boundary when the neighbor has no pit. But according to the opinion of Rava, who maintains that it is prohibited to dig a pit near the boundary under any circumstances, the ruling of this mishna is difficult.

The Gemara explains: Rava could have said to you: Wasn’t it stated with regard to that mishna that Abaye says, and some say it was Rav Yehuda who says: We learned that the mishna means: From the wall of his pit? This indicates that the neighbor must distance the edge of his pit from the boundary by the thickness of his wall, which is three handbreadths. Therefore, even according to the ruling of the mishna, one may not dig his pit directly adjacent to the boundary.

There are those who say this discussion in the form of a challenge to the opinion of Abaye. The mishna teaches that one must distance his pit from that of his neighbor, and it was stated with regard to that ruling that Abaye says, and some say it was Rav Yehuda who says: We learned that it means: From the wall of his pit. In other words, the edge of the neighbor’s pit must be three handbreadths away from the boundary. Granted, according to that first version of the dispute, in which you said: All agree that he may not dig or place them close to a field of his neighbor if that field is designated for digging pits, one can explain that the mishna is referring to a field that is designated for digging pits.

But according to that second version of the dispute, in which you said that they disagree with regard to a field that is designated for digging pits, there is a difficulty. Granted, this works out well according to the opinion of Rava, who says that it is prohibited to dig a pit near the boundary in this case. But according to the opinion of Abaye, the ruling of this mishna is difficult, as if the mishna is referring to the wall of the neighbor’s pit, this indicates that the first pit was dug close to the boundary.

The Gemara explains: Abaye could have said to you: The mishna is referring to the specific case where both neighbors came to dig their pits at the same time. Consequently, they must both distance their pits from one another. If there is no pit as yet next to the boundary, and the neighbor is not digging at that point, one may dig his pit alongside the boundary.

The Gemara suggests: Come and hear a proof from a baraita: In the case of rock that is so soft that it crumbles in one’s hands, and no tool is needed, this one may dig his pit from here, and that one may dig his pit from there. This one distances his pit three handbreadths and plasters with lime, and that one distances his pit three handbreadths and plasters with lime. This indicates that the first one who digs a pit must distance his pit even when the second one does not yet have a pit. The Gemara rejects this proof: Rock that crumbles in one’s hands is different. In this case, one must maintain a distance from the boundary due to the softness of the ground.

The Gemara is puzzled by this exchange: And he who asked it, why did he ask it? The baraita is explicitly referring to rock that crumbles in one’s hands, so this is clearly a unique case. The Gemara answers that the Sage who asked the question assumed that the halakha of the baraita includes all types of soil, and he thought that it was necessary for the tanna to mention the specific example of rock that crumbles in one’s hands, as it could enter your mind to say that since this substance crumbles in one’s hands he is required to keep his pit at an even greater distance. To counter this, the baraita teaches us that a distance of three handbreadths is sufficient.

The Gemara suggests: Come and hear a proof from the mishna: One must distance the solid residue of produce that has been pressed free of its oil, and animal manure, and