Rashi on Deuteronomy 19:14/רש"י על דברים י״ט:י״ד

1לא תסיג גבול THOU SHALT NOT REMOVE [THY FELLOW-MAN’S] LANDMARK — תסיג is of the same meaning as (Isaiah 42:17) “they are turned back (נסגו אחור)”. The meaning is, that one moves the mark that shows the division of the land (i.e. the division between two adjoining fields) backwards into the field of his neighbour in order thereby to enlarge his own. — But does it not already state. (Leviticus 19:13) “Thou shalt not rob”, why, then, is it also commanded “Thou shalt not remove the landmark”? It teaches that one who obliterates his neighbour’s border line transgresses two negative commands (לא תגזול and לא תסיג). One might think that this is the case also if one does so outside the Land of Israel! Scripture, however, states, “in thine inheritance which thou shalt inherit [in the land]”;— thus in the Land of Israel one who does this transgresses two negative commands, whilst outside the Land he transgresses only the command of לא תגזול (Sifrei Devarim 188:1-2).