Or HaChaim on Genesis 13:17/אור החיים על בראשית י״ג:י״ז

1 קום התהלך בארץ. "Arise, and walk through the land." The Talmud Baba Batra 100 discusses how one acquires title to land. [The context of the discussion is whether the fact that people used someone's private property as a shortcut entitles them to continue to do so even if the property in question changed hands. Ed.] Rabbi Eliezer, basing himself on our verse, claims that merely traversing the land assures one of one's rights to the area one has traversed; the other rabbis hold that one has to go through the regular legal procedure for acquiring title. The rabbis say that our verse is not to be taken as a general rule, but that an exception was made in the case of Abraham who was especially beloved of G'd. G'd intended to facilitate Abraham's descendants taking possession of the land when the time came. According to these rabbis, Abraham's title to the land stems from verse 15 where G'd had promised it to Abraham. The reason G'd rolled the land up so as to bring it close to Abraham was in order that the act of moving it would demonstrate ownership by the person on whose behalf it was moved.