What was Hashem doing atop the ladder?
Rashi: He was guarding Yakov. 1
Tosfos ha'Shalem (8), from Bereishis Rabah 69:3: Why did he need to be guarded? The angels saw that his face resembled that on the Kisei ha'Kavod, and wanted to kill him, lest it look like there are two Powers. Hashem burned them.
Hashem promised him and his children the land on which he was lying. That is not very much land!
Rashi: This teaches us that Hashem compressed the whole of Eretz Yisrael underneath him 1 - a sign that it would be as easy to conquer as four Amos [if they will deserve it].
Seforno: This promise actually refers to Chutz la'Aretz, where Yakov was currently lying. And it is an assurance that he would be a prince of G-d among the inhabitants of the land, like Avraham and Yitzchak were.
Ha'Emek Davar : The land that you are on now (Eretz Yisrael), which was promised to Avraham and Yitzchak, is for you, and not for Esav.
Tosfos ha'Shalem (5): What happened to the inhabitants at the time? Hashem made a place for them under the land - "umi'Tachas Zar'os Olam."
Tosfos ha'Shalem (15) citing the Tur: Hashem gave to him the place of the Mikdash, which is primary - automatically, the rest belongs to him.
Da'as Zekenim, Hadar Zekenim: This is like when they give a small land to great soldiers, and through their valiance they conquer all around it.
Why does it say "Avicha" regarding Avraham, and not Yitzchak? It is more appropriate for Yitzchak!
Hadar Zekenim, Riva: Avicha does not refer to Avraham, rather, to "Elokei". I am Elokei Avicha - Elokei Avraham, Elokei Yitzchak.
Moshav Zekenim, Tosfos ha'Shalem (2) citing R. Efrayim: Yakov lived 15 years in Avraham's life. Avraham cherished him, and called him "my son." Yitzchak loved Esav more than Yakov. 1
Tosfos ha'Shalem (5): Grandchildren are like children. Even the Brachos of Yitzchak were in the merit of Avraham.
Ohr ha'Chayim: This is to teach that Yakov will inherit directly from Avraham; it will not go via Yitzchak. This eliminates any claim that Esav might have. 2 It is not needed to exclude Yishmael, who is a Shifchah's son; he belongs to Yitzchak. "Yerushah l'Esav Nasati Es Har Se'ir" (Devarim 2:5)
This is astounding. When Yitzchak realized that he blessed Yakov by mistake, he said "Gam Baruch Yihyeh"! He saved Birkas Avraham and Eretz Yisrael to give them to Yakov! Some say that Esav refused to be circumcised (refer to 25:25:1:2)! Perhaps they mean that Yitzchak showed more love to Esav, to try to draw him close (PF).
If this prophecy negates Esav's claim, it could equally have said that Yitzchak inherits Avraham, and Yakov is Yitzchak's only heir! (PF)
Why do we find that Hashem stood over Yakov, but not over Avraham and Yitzchak?
Rosh (Bereishis 42:1): The king does not stand over his field when it is plowed or seeded, only when the crops are piled up. Hashem told Avraham to go in the land, and "va'Yizra Yitzchak", but it says about Yakov "Kodesh Yisrael la'Shem Reishis Tevu'aso."
Malbim: The Torah says so to show one of the four ways 1 in which this was inferior to Moshe's prophecy. It seemed that Hashem was standing. 'Seeing' applies to prophets, who saw semblances
Malbim (12): The others are
QUESTIONS ON RASHI
Rashi writes that Hakadosh-Baruch-Hu does not attach His Name to Tzadikim during their lifetime. Why did Hashem say "Elokei Yitzchak", even though Yitzchak was still alive?
Rashi: The reason (that there is no guarantee that the greatest Tzadik will not still sin), was not applicable in the case of Yitzchak, who was blind and housebound. 1
Malbim (Torah Ohr 1): Through Avraham and Yitzchak, Hashem caused His Shechinah and Elokus to dwell in Eretz Yisrael, therefore He will give it to Yakov.
In which case he was considered like dead, devoid of the Yeitzer-ha'Ra.