Bava Batra, Chapter Two, Mishnah Twelve
Mishnah twelve deals with distancing trees from the another persons fields.
1) A person may not plant a tree near anothers field unless it is four cubits away, no matter whether it be a vine or any other kind of tree.
a) If there was a wall between, each may plant up to the wall on either side.
b) If its roots entered within the others property, the other may cut them away to a depth of three handbreadths so that they shall not hinder the plough.
i) If he dug a cistern, trench or cave, he may cut them away as far down as he digs, and the wood shall belong to him.
A tree planted close to another persons property will eventually grow onto that property, both above and below ground. Therefore a person was required to distance his trees four cubits from anothers property.
The remainder of the mishnah is basically refining this general law which we learn in section one. In 1a we learn that the law is not applicable if there is a fence, which would prevent the leaves of the trees from entering into the neighbors property. If there is a fence than one may plant his trees right up to the fence. In 1b we learn that if the roots of your neighbors tree enters your property you are allowed to remove the roots that are less than three handbreadths deep, so that the plow will not get caught on them. Finally, we learn at the end of the mishnah that if one was digging something on his property and the roots interfered, he can cut them away even further than the aforementioned three cubits.
Questions for Further Thought
· In the last clause of the mishnah it says that the trees (i.e. cut away roots of trees) are his. Why doesnt he have to return them to the owner of the tree?