Why did Hashem refer to Himself as "the G-d of Yaakov's father," i.e. Yitzchak?
Ramban: Refer to 46:1:1:2**.
Seforno: 'I am Hashem who instructed Yitzchak not to go down to Egypt, 1 and I am now instructing you not to be afraid to do so!'
Ohr ha'Chayim: Just like your father did not taste servitude and affliction, you will not, even though you descend to Egypt.
Malbim: My Elokus clings to you, like it clung to your father.
Ha'amek Davar: You prayed and offered Korbanos to Elokei Yitzchak (46:1) for supernatural influence regarding income, like Yitzchak's Midah. This will happen in Egypt. When Yaakov first came, the Nile rose and the decree of famine ceased. As long as Yisrael was there, the great nation was financed with wondrous Hashgachah. A woman would draw [from the river] half water and half fish (Yoma 75a).
Why did Yaakov and his children have to go to Egypt in order to become a great nation?
Seforno: Because as long as they lived in Kena'an, there was nothing to stop them from assimilating with the Kena'anim; whereas the Egyptians, who refused even to eat with the Ivrim, would never allow that to happen. 1
See 43:32.
What was Yaakov's fear? If it was of Galus, why should he not fear?
Ohr ha'Chayim: Presumably, Avraham told his children of the exile decreed at the Bris Bein ha'Besarim, 1 and so Chazal (Bereishis Rabah 82:13) said. When Yaakov saw that there was "Shever" (42:1) in Egypt, meaning that his children will suffer in exile there, he feared lest the exile begin with him, and lest he be buried in a Tamei land. Hashem quieted these concerns. Refer to 46:3:152:1; 46:4:1:1; and 46:4:2:4.
Malbim: Yaakov feared six matters. (a) His children would mix among the Egyptians; refer to 46:3:152:3. (b) Perhaps they will be diminished. Hashem responded, "l'Goy Gadol Asimcha"! (c) Yaakov feared that Shem Elokus would not rest upon him; refer to 46:4:151:3. (d) Perhaps he would be buried in Chutz la'Aretz; refer to 46:4:1:1. (e) Perhaps his children would remain there forever; refer to 46:4:2:6. (f) Perhaps Yosef will die in his lifetime; refer to 46:4:3:3.
Ha'amek Davar: Yaakov feared lest his children mix among the Egyptians. Only in Eretz Yisrael, a place sanctified for Avodah of Korbanos, and unique for Chochmah of Torah far more than other lands, the aspect of Yisrael can be guarded for all generations. In Egypt, the special quality of Yisrael could sink! Hashem promised him that it will not.
See 15:13-14.
Why does it say "l'Goy Gadol," and not, 'Goy Gadol?'
Ohr ha'Chayim #1: Do not think that you will be there only during the famine. I want to put you there for the sake of a great nation. The Rashbi and his close Talmidim said that the purpose of exile is to clarify parts of Kedushah scattered among branches of Kelipos (shells). Since Egypt was full of idols, the great Tum'ah there captured many great parts of Kedushah. From the day that Adam sinned, an evil Shifchah ruled over sparks of Kedushah. The nation that stood on Sinai had been captive in Kelipos of Egypt. This Goy Gadol was lost there in the Kelipos. Only Yaakov, via his awesome Kedushah, can siphon the Kedushah from there. This is why Chazal said (Bereishis Rabah 79:1) that Yaakov did not die until he saw 600,000 of his descendants. 1 Afterwards they were afflicted and refined in the iron cauldron in the affliction of Egypt, and came out clarified.
Ohr ha'Chayim #2: Hashem explains to Yaakov why his children must suffer the servitude and affliction - it is needed for the great nation [that will emerge].
Malbim, Ha'amek Davar from Pesikta Zutresa Devarim 46a: Yisrael will be a distinct nation there; they will be distinguished (and not mix with the Egyptians).
Ha'amek Davar: This is like it says "v'Isheru Eschem Kol ha'Goyim, Ki Sihyu Atem Eretz Chefetz " (Mal'achi 3:12) - not like other nations, who are called 'Goy' only if they have their own kingship and land. Rather, [Yisrael] themselves are Eretz Chefetz. They are called 'Goy' even without their own kingship and land. 2
Yefe To'ar (on the Midrash): It is possible to grow from 70 to 600,000 in 17 years if they begat from the age of six, six children at a time, every seven months. However, Shemos 1:6-7, 12 implies that they multiplied greatly only later! Also, if so, why does it say that Yosef saw three generations from Efrayim in his lifetime (50:23)? (Other Shevatim saw four generations within 17 years! - PF) Rather, he saw with Ru'ach ha?Kodesh that 600,000 will descend from his sons. (Can we say that in 17 years, Yisrael grew about 10,000 times, and in 193 years, including the slavery, about which it says "v'Cha?asher Ya'anu Oso Ken Yirbeh v'Chen Yifrotz", they grew only five times?! Even according to the opinion in Tanchuma (Beshalach 1, Warsaw edition) that only one out of 500 survived Makas Choshech), they grew only 500 times in the 193 years! However, 'did not die until he saw?' implies seeing living descendants. Perhaps he saw descendants equal to 600,000. We find people equal to 36, 70 or 50,000 people (Brachos 62b, Bava Basra 121b, Sotah 35b); Moshe was like 600,000 (Devarim Rabah 11:9)? ? PF)
Ha'amek Davar: The simple meaning is, also here 'Goy' is with their own kingship and land. In Egypt they will become qualified for this.
