Rashi on Deuteronomy 34:3/רש"י על דברים ל״ד:ג׳

1ואת הנגב means THE SOUTH COUNTRY. — Another explanation is, that it refers to the cave of Machpelah (which was in the Negeb), as it is said, (Numbers 13:22) “And they went up to the south country, and came to Hebron” (where this cave was situated) (Sifrei Devarim 357:20).

2ואת הככר AND THE PLAIN — He showed him Solomon casting the vessels of the Temple, as it is said, (1 Kings 7:46) “In the plain (ככר) of the Jordan did the king cast them in the thick clay” (Sifrei Devarim 357:21).