Only in Egypt would he grow into a great nation. The posuk says Behold a nation has come out from Egypt (Bamidbar 22:5). The Torah was received outside of Israel, in the desert.
Chazal say, What are the spaces in the Sefer Torah used for? To give Moshe the opportunity to reflect between sections. This matter of Yaakov going into exile is very profound. A person's intellectual ability is not sufficient to understand or comprehend it. Therefore, this Parsha is closed. There are no spaces. From here we can learn that one should not lose hope during the period of time known as 'The Heels of Moshiach'. Each successive generation is on a lower level than the previous one. We are afraid. How will we merit the Redemption? However, it's specifically in the exile that we will achieve holiness. This is the Will of Hashem. I heard in the name of R' Bunim from P'shischa that although the Neshamos (souls) are becoming smaller and diminished in each generation, the point of holiness in the heart becomes more immaculate and pure in each generation.
The posuk (Bereishis 48:19) says that Menashe's brother, the small one, will be greater than Menashe. Because he made himself small, he will merit greatness. This teaches us to what extent Hashem hates the traits of pride and selfishness and how much He loves the trait of humility.
The Medrash had a difficulty understanding the posuk. It is known that when people wage war, they start from far away. Afterwards, if necessary, the war is waged closer to the enemy. The posuk should have been reversed: My bow and my sword. A bow kills from far away and a sword from up close. Therefore, the Medrash says the posuk is talking about Mitzvos and Maasim Tovim. These are the weapons in the war against the Yetzer Hora. This war is fought completely opposite from a physical war. In this spiritual confrontation, a person needs to first fight up close. The Yetzer Hora begins to try and rule over a person upon his exit from the womb, Sin crouches at the doorway (Bereishis 4:7 - see Sanhedrin 91a). Hashem helps a person to drive the Yetzer Hora away. The person then needs to stand guard all of his life and shoot arrows from a distance to keep the Yetzer Hora at bay. That's the meaning of the posuk, That I took from the Emorite with my sword and with my bow - with the merit that I gained from my war against the Yetzer Hora from near and from a disstance. How? Through doing Mitzvos and Maasim Tovim.
It appears, that in the World to Come, groups of people are considered nations according to their belief in Hashem and the greatness of their actions. In this world they may have been from many nations. Behold, there were many Tzadikkim: Odom, Shais, Misooshelach, Shaim and Aiver, and many others aside from the Avos (Patriarchs). That is the meaning of our posuk, I shall be gathered to my nation. His burial was next to his fathers amongst the 'nation' of the righteous.