What is the significance of the fact that 'Hashem ascended from upon Yaakov'?
Seforno: Refer to 17:22:1:3.
Ramban: This teaches us that this was not just a sort of dream, 1 but that the Shechinah actually rested upon Yaakov, 2 as it did on Avraham in Lech Lecha, where the Torah uses the same expression. 3
Malbim: When a Navi prepares himself for prophecy, it does not depart until his clinging [to Hashem] ceases. Here, the prophecy came without preparation, to tell Yaakov about the future, so Hashem departed once the prophecy ended.
Why does the Torah find it necessary to add, "ba'Makom Asher Diber Ito Elokim"?
Rashi professes not to know what this is coming to teach us. 1
Seforno: This is referring, not to Yaakov's current vision, but to when Hashem appeared to him on his way to Charan in the dream with the ladder - on exactly the same spot where he was now. And now, as soon as Hashem departed, Yaakov set up the Matzevah and poured a libation on it. 2
Malbim: This teaches that the prophecy was due to the place; the place was prepared for the light; it returned above and was hidden there.
QUESTIONS ON RASHI
Rashi writes: "'At the place where He had spoken with him' - I do not know what this teaches us." What might it teach us?
Gur Aryeh: The verse teaches us that Yaakov was aware that it was the sanctity of the place brought about Hashem's revelation. It is a unique location; and Yaakov knew this when he named it "G-d is in Beis El" (Rashi to 35:7) - a name unlike any place where Hashem had appeared to Avraham and Yitzchak.
