(Devarim, Ibid. 6) "And He buried him in the valley, in the land of Moav": If "in the valley," why "in the land of Moav"? And if "in the land of Moav," why "in the valley"? To teach that Moses died within the inheritance of Reuven and was buried in a field in the inheritance of Gad.
"and no man knew his grave": Some say that even Moses did not know the place of his burial, it being written "and no man knew his grave," "man" signifying Moses, as in (Bamidbar 12:3) "And the man, Moses, was exceedingly humble." And it once happened that the emperor's house sent (a deputation, telling them) "Seek out the grave of Moses." They went. When they stood above, it (his grave) seemed to be below. When they stood below, it seemed to be above. They then divided themselves into two groups (one above, and one below), but to those who stood above, it seemed to be below; and to those who stood below, it seemed to be above — this in keeping with "and no man knew his grave."