The beginning of “Hashem your Elokim will expand your borders” came about through Moshe giving an inheritance to half of the tribe of Menashe on the other side of the Jordan. This was specifically through the tribe of Menashe, whose spiritual service is “nashani” — to jump away and flee from the state of forgetfulness associated with “my father’s house.”
We need to understand: Why did Moshe give half of the tribe of Menashe an inheritance on the other side of the Jordan, when they had not asked for it?
The explanation is: All matters come through Moshe. Since in the future there will be the fulfillment of “Hashem your Elokim will expand your borders,” the beginning of this was through Moshe giving an inheritance to half of the tribe of Menashe on the other side of the Jordan.
This is why the Midrash explains that the hint found in the offerings of the nasi of Menashe is connected with the fact that they received two inheritances, on both sides of the Jordan. From this it is understood that this was something positive and elevated.
In the request of the tribes of Gad and Reuven, there was also an undesirable element, because they gave up their portion in Eretz Yisroel. This was not the case with the tribe of Menashe. Their inheritance on the other side of the Jordan was connected with the future inheritance of the land in the time to come. Therefore, they received their portion “half on the other side of the Jordan and half in the land of Canaan,” emphasizing that this was not a renunciation of Eretz Yisroel, since they also received a portion in Eretz Yisroel itself.
The reason that an inheritance similar to the future inheritance was given specifically to the tribe of Menashe is because they had a special love for the land, as seen from the story of the daughters of Tzelafchad, who were “from the families of Menashe, son of Yosef.”
To explain this further: The spiritual content of Menashe’s service is the service that comes through remembering, even while being in a place that seeks to make him forget “my father’s house.” The service of Menashe is “nashani” — to jump away and flee from the state of forgetfulness.
Since the true state of “my father’s house” will be revealed in the future redemption, therefore it was specifically the tribe of Menashe that received an inheritance resembling the future inheritance of the land.
This also explains why there were cities of refuge on the other side of the Jordan. At first glance, why would a Levi want to live on the other side of the Jordan? The tribe of Levi cherished Eretz Yisroel and did not stumble in the sin of the spies.
The explanation, based on the above, is that the inheritance on the other side of the Jordan contains a reflection of the future era, when the Jewish people will also inherit the lands of the Keni, Kenizi, and Kadmoni.