In Parshat Shoftim (Dvarim 19:14) we read: “Do not move a boundary of your neighbor, which the early ones marked out in your inheritance, which you shall inherit in the Land that HaShem, your God gives you to possess it.”
Why do we need to be told “Lo tasig gvul re’echa”, “Do not move a boundary”- Isn’t it obvious that by moving our boundary we would be stealing land from the neighbor’s property? Shouldn’t that already be covered in “Lo Tigzol”, “Do not steal” (Vaikra 19:13)?
Rashi explains that a person who overturns his neighbor’s boundary violates both of these negative commandments.
Does this also apply outside of the Land of Israel?
Rashi states that if you overturn your neighbor’s boundary in the Land of Israel then you violate two commandments. But outside of Israel, you only violate the commandment of “Do not steal.”
According to Ramban, this verse is a warning against changing the boundaries of the division by which the nesiim (princes) appointed the Land to the tribes or to any individual among them. Therefore, he mentioned the “early ones” (Yehoshua, Eleazar and the tribal leaders) and mentioned “in your inheritance, which you shall inherit…” The reason for this commandment is that no one should contemplate to say, “My portion which they gave me is not as valuable as the portion on my friend, because the dividers erred,” or he may feel suspicious of the lots, thus he will not consider the removal of the boundary marker to be robbery at all. Therefore it is commanded here that no one should controvert that division and he may not make any change in the boundaries, either secretly or openly.
Ibn Ezra adds that although moving boundaries may not sound like such a big deal, it can lead to arguments, fighting and even murder.
We see that by moving boundaries, one violates two commandments and may even be endanger their life. Do we need any more proof that it should not be done?