What is the significance of the borders of Eretz Yisrael that the Pasuk spells out here?
Rashi and Rashbam: From the Yam-Suf in the east 1 to the Mediterranean Sea in the west, 2 and from the Sinai Desert in the south to the River P'ras in the north. 3
Pesikta Zutr'sa: This will be in the future, since we do not find that the borders of Eretz Yisrael have ever been from the Desert to the river or from the Yam- Suf to Yam P'lishtim.
Oznayim la'Torah: Seeing as the Yam-Suf - in the south - and the Mediterranean Sea - in the west - are not opposite each other, nor are the desert - in the east - and the River P'ras - in the north - the Pasuk is merely specifying four border points 4 - including two large seas, opening to trade opportunities, one by the desert and one by the River P'ras.
See Rashbam, Devarim 1:1 (DH 'Mol Suf').
As indicated in Yeshayah, 9:11 (Rashbam).
As indicated in Yirmiyah, 1:14 (Rashbam).
Oznayim la'Torah: Which the Torah explains in detail in Mas'ei
What does the Torah mean when it writes "Ki Etein be'Yedchem es Yoshvei ha'Aretz ... ve'Gerashtamo mi'Panecha"?
Seforno: Expelling the Cana'anim from the land lies in the hands of Yisrael. And Hashem is exhorting them here not to be lax in going about achieving it. 1
See Yehoshua, 18:3, how Yehoshua castigated them when they were lax (Seforno).