Why did Yitzchak insert the B?rachah of Avraham and of Eretz Yisrael here (but not in the B?rachos that he thought he was blessing Eisav)?
Rashi: He was referring to the B?rachah of "ve'E'escha le'Goy Gadol" and "Vehisbarechu be?Zar'acha Kol Goyei ha'Aretz" said to Avraham - that that nation and those blessed descendents would descend from him. 1
Seforno (in 27:29): This refers to the B?rachah of Eretz Yisrael, which was reserved for Ya?akov exclusively. 2 Malbim - the B?rachah of inheriting Eretz Yisrael is also mentioned with seed, on which Hashem will put His Shechinah, because they are interdependent. He attributed this B?rachah to Hashem, since it is not in the hands of man. 3
Rashbam: If he will not marry a woman from the Cana'aniyos 4 (who are slaves), he will merit to inherit the land in which he is currently sojourning.
See Sifsei Chachamim.
Refer to 27:29:2:1. The Seforno adds here that the B?rachah of "Birkas Avraham" - "Veh?yei B?rachah" which is synonymous with teaching the people the knowledge of Hashem - (together with his children) will create the Kidush Hashem that is necessary to inherit Eretz Yisrael). The Oznayim la'Torah adds that Yitzchak reserved the B?rachah of Avraham for Ya?akov, 'the Ish Tam Yoshev Ohalim' who is worthy of it and of inheriting Eretz Yisrael.
As the Malbim explained earlier .Refer to 27:1:153:2.
Just as Avraham had instructed Yitzchak.
QUESTIONS ON RASHI
Rashi writes: "'Avraham's blessing' - [i.e.] that HaSh-m had said to him, 'I shall make you a great nation' (12:2); and '[the nations] shall bless themselves by your progeny' (22:18)." How does Rashi know that the reference is to these blessings in particular?
Gur Aryeh: Other blessings applied to Avraham personally (e.g. "I shall bless those who bless you" - 12:3); how is Yitzchak able to give them over? The two blessings Rashi cites refer to Avraham's offspring; and Yitzchak blessed Yaakov that he would become that great nation.
