Sforno on Deuteronomy 34:6/ספורנו על דברים ל״ד:ו׳

1ויקבור אותו, if Moses buried himself, as is the opinion of some of our commentators, (compare Rashi) it would have been his disembodied soul that accomplished this, for it is stated clearly that his body died on the summit of the mountain from which he viewed the Holy Land, as the Torah wrote in verse 5: “Moses died there.” On the other hand, the burial is described in our verse as having taken place in the valley.