You shall not remove your neighbor's landmark, which the men of old time have set, in your inheritance which you shall inherit in the land that the LORD your God gives you to possess it.
Read Chapter 19
Ambrose of Milan
But on the contrary, if your eye has looked upon a woman to covet her, you have opened a wound, you have driven a weapon into your body. Your very members become tools of sin. If you look upon the property of orphans and drive them from the dwellings of their fathers, you are changing the landmarks that your forefathers set. Your members are tools of iniquity. And so the passions are the author of guilt and not the flesh, for the flesh is the servant of the will. .
And since we have taken an example drawn from agriculture, enjoin them to keep the laws about borders intact and to guard the ancestral boundaries which the law protects. The good will of a neighbor is often more important than the love of a brother. For a brother is often far away, but a neighbor, close at hand, is a witness to the whole of one’s life and a judge of one’s dealings. ()..
Landmarks, either which divided the tribes, or the inheritance of individuals. The former were strictly kept up till after the captivity. Those who removed the latter were to be scourged for theft, and again for disobeying this law. (Selden, Jur. vi. 3.) Josephus ( iv. 8,) understands that encroachments on the territories of others, which give rise to many wars, are hereby prohibited. (Calmet)
So are likewise innovations in religion. The Romans had a superstitious veneration for these landmarks, which they adored under the name of the god Terminus, (Haydock) crowning them with flowers, and offering cakes and sacrifices to them. Spargitur et coeso communis Terminus agno. (Ovid, Fast.)
They punished the crime of removing them either with death, banishment, or a fine.