There was a terrible famine all throughout the middle east. Jacob and his family did not have the food they needed to survive. Thanks to Joseph's talent in interpreting dreams, and his leadership in preparing for the famine, Egypt had enough food, and was selling it to people in need. Jacob begrungingly sent 10 of his sons to Egypt with riches, in order to buy food for the family. Benjamin-- the youngest child-- stayed home with Jacob.
ויפג לבו AND JACOB’S HEART CONTINUED COLD — his heart passed away (נחלף) and ceased to believe — his heart took no notice of their words. The word ויפג has the same meaning as (Beitzah 14a) “all spices let their taste pass away (מפיגין)” (i.e. lose their taste) in Mishnaic Hebrew. Similar is (Lamentations 3:49) “without (הפגות) intermission”. The words (Jeremiah 48:11) “and his scent is not changed (נמר)” is rendered in the Targum by “and his scent has not את כל דברי יוסף.
(1) So Israel set out with all that was his, and he came to Beer-sheba, where he offered sacrifices to the God of his father Isaac. (2) God called to Israel in a vision by night: “Jacob! Jacob!” He answered, “Here.” (3) And He said, “I am God, the God of your father. Fear not to go down to Egypt, for I will make you there into a great nation. (4) I Myself will go down with you to Egypt, and I Myself will also bring you back; and Joseph’s hand shall close your eyes.” (5) So Jacob set out from Beer-sheba. The sons of Israel put their father Jacob and their children and their wives in the wagons that Pharaoh had sent to transport him;
אל תירא מרדה מצרימה FEAR NOT TO GO DOWN TO EGYPT — God said this to him because he was grieved that he was compelled to leave the Land of Israel (Pirkei DeRabbi Eliezer 39).
"...the Rabbis pictured Jacob pondering whether to remain in Canaan or to settle in Egypt. Had God not expressly forbidden Isaac to go there? And had Abraham not encountered grave dangers in Egypt? Should he, Jacob, now be the one to forsake the promised land? The Midrash (Midrash HaGadol, Midrash Lekach Tov) says that he finally decided to leave because the decision was God's and not his.
(2) The LORD had appeared to [Isaac] and said, “Do not go down to Egypt; stay in the land which I point out to you.
"The fear alluded to here is not connected with Jacob's personal feelings. It is a part of the symbolic or archetypal dread of the founder of the nation of the spiritual consequences of of leaving the homeland and going to Egypt."
אל תירא מרדה מצרימה, “do not fear descending to Egypt;” no one in the Bible had ever been told by G-d not to be afraid, unless he had already been afraid. Yaakov’s reasoning for being fearful was his knowledge that being strangers in a foreign land and being slaves which had been decreed already in the lifetime of his grandfather Avraham would most likely commence now that he was moving to Egypt. G-d answered him that although He had warned his father and grandfather of this, He appeared to him in order to give him reassurance. He hinted that although he was correct in assuming that the warning would soon be fulfilled, but by the same token, the promise made to all the three patriarchs that they would develop into a great nation, came closer to its fulfillment.
אל תירא…כי לגוי גדול אשימך שם "Do not be afraid…for I will make you into a great nation there." What precisely was Jacob afraid of when he set out to go to Egypt? If it was the fear of ushering in exile for his family, how did G'd's assurance alleviate that fear? If, on the other hand, G'd meant to console him that there would be no exile there, history teaches that Jacob's family became enslaved and suffered persecution and hard labour in Egypt! Besides, how did the announcement that Jacob would become a great nation while in Egypt console him over what he was afraid of? Why could he not develop into a great nation in any other place but Egypt?
"... his joy immediately begat fear again in his soul, respecting his departure from his national laws and customs; for he knew that youth is by nature prone to fall, and that in foreign nations there is great indulgence given to error; and especially in the country of Egypt, a land in a state of utter blindness respecting the true God, in consequence of their making created and mortal things into gods. Moreover, the addition of riches and glory is a snare to weak minds, and he also recollected that he had been left to himself, as no one had gone forth out of his father's house with him to keep him in the right way, but he had been left solitary and destitute of all good instructions, and might therefore be supposed to be ready to change and adopt their foreign customs. Therefore, when that Being who alone is able to behold the invisible soul, saw him in this frame of mind, he took pity on him and appearing unto him by night while he was lying asleep, said unto him: "Fear nothing about your departure into Egypt; I myself will guide you on your way, and will give you a safe and pleasant journey; and I will restore to you your long lamented son, who was once many years ago believed by you to have died, but who is not only alive, but is even governor of all that mighty country."
Jacob was afraid that his seed would be absorbed by the Egyptian nation. Only in the land of Israel could the unique Jewish spark be preserved down the ages. It was on this score the Almighty reassured him: "Fear not, for there I shall make of thee a great nation." Our Sages interpreted the phrase "great nation" to imply that the Jews would preservetheir national identity, and not be absorbed into Egypt.
Rabbi Hiyya bar Abba said in the name of Rabbi Yochanan: By rights, Jacob should have gone down to Egypt in chains of iron. But his merit availed him, as it is said "Because of my love for Jacob, I drew Israel with chords- my bands of love. Thus I was to Israel as one who lifts the yoke from the jaws of animals, making it easier for Israel to sustain the burden of servitude."
About Jacob going down to Egypt, Rabbi Berekhiah in the name of Rabbi Judah bar Simon told this alegory: An attempt was made to drag a cow to the slaughterhouse, but she refused to move. What was done? Her young one was pulled ahead of her, and she reluctantly, unwillingly, followed. So too, Jacob should have gone down to Egypt in shackles with an iron collar about his neck. But the Holy One said: Shall I have my firstborn son go down in such disgrace? Even if I induce Pharaoh to bring him down personally, I will not have Jacob's going down turned into a public spectacle. Instead, I stall draw Jacob's son in front of him, and then [on his own] reluctantly, unwillingly Jacob will quietly follow.
Another interpretation: "With Joseph, He was brought down to Egypt (Genesis 39:1)" Joseph brought down the Presence with him to Egypt.
Said the Holy One blessed be He to Moses: I said to their father Jaob: "I will go down with thee into Egypt; and I will surely bring thee up again." Now I have come here to bring out his descendants, in accordance with My promise to their forefather, Jacob. Where will take them to? To the place from whence they came forth, to the land which I swore to their fathers, as it is written: "To bring them up out of that land." (Ex.3:8).
