Based on the Dvar Malchus of the Shabbos Parshas Vaeschanan, 5751
Since in fact both are read on the same Shabbos, there is a connection between the two. What is the connection then between "Nachamu Nachamu" and parshas Vaeschanan?
Double comfort
The Chazal explain that the repetition of the word Nachamu tells us that Hashem comforts us over the destruction of the first and second Batei Mikdash.
The Rebbe Melech Hamoshiach explains that the true and complete redemption is a double comfort, because it will be an unlimited redemption. This redemption will lack nothing and will have all of the plusses possible.
During the first Beis Hamikdash, everyone knew and even saw that Hashem dwelled in it. It had the aron habris, the urim vitumim that answered with ruach hakodesh, a fire would come down from heaven, and more.
The second Beis Hamikdash didn't have these miracles and the g-dly revelation wasn't as great as the first one, yet at the same time it was more connected to this world. The second was bigger than the first one and lasted longer.
The third Beis Hamikdash will be unlimited and will have all of the plusses. The biggest revelation will take place within it. Whoever enters will feel Hashem's presence mamash, yet it will all take place in our physical world and will last forever.
Our avoda will bring about the complete redemption
Such an unlimited revelation will not happen by itself. Chassidus explains that as a result of our avodas Hashem, Torah learning, and fulfilling mitzvos in this physical world during the golus, we will see and feel this tremendous revelation.
If Moshe would have entered the Land of Israel, the redemption and conquest of the Land would have been immediate, and the Beis Hamikdash would have lasted forever. Such accomplishments would have been without our input, without our avodas Hashem. If the redemption would have been then, it would have been unlimited and so amazing.
Hashem made things happen that Moshe wouldn't enter Israel. Instead, Yehoshua would lead the Jewish nation in. As a result, we would have to work hard in order to conquer the Land, slowly but surely. Even then, the conquest of the Land wouldn't be complete, for afterwards we were sent into exile to Bavel and Rome, when we were spread out all over the world and in such places learned Torah and performed mitzvos.
As a result, through our efforts and avodas Hashem in this limited and physical world, without miracles or special assistance from Above, the unlimited redemption will come about. The redemption will start from Above and continue to flourish here in this world due to our avoda. This time, conquest of the Land will be immediate, miraculous, and everlasting.
In light of the above, on Shabbos Vaeschanan, when we read in the Torah that Hashem leaves Moshe in the desert and sends the Jewish nation into Israel with a difficult job to do, we read the haftorah of "Nachamu Nachamu" for the double redemption that will come about due to our avodas Hashem.
Wonders!
At this point in the farbregen, the Rebbe Melech Hamoshiach Shlita shows us how we are able to see the unlimited wonders of the redemption. Imagine, now, (in the year 5751), that in Moscow Russia, Chassidim get together and farbreng and are organizing the kinus hashluchim. The topic of the farbrengen is "A person should help his friend", how to disseminate Chassidus all over Russia. Not long ago the Russian government opposed and fought anything that had to do with Raboseinu Nisieinu, especially disseminating the wellsprings of Chassidus. Now its government is helping to arrange the kinus and is honoring all of the shluchim!
When we see such an awesome miracle, we anticipate the rest of the wonders of the true and complete redemption that the Rebbe promised would happen this year, the year that "I will show you wonders".
In actuality – mamash
We already want so much to taste from the unlimited redemption. We can already do this by adding without limitations in our Torah learning and mitzvah performance.
The Chazal said that starting from the fifteenth day of the month of Av, whoever adds in Torah learning, "...Hashem add life onto his life..." The Rebbe Melech Hamoshiach says that whoever learns Torah without limitations, more than what he/she normally learns and thinks they can learn, Hashem will add on unlimited time to his life, to the extent of living forever!
As such, starting from the fifteenth of Av this year, all of us should add in an unlimited manner in our Torah learning, especially in learning that has to do with the redemption and Moshiach.
"...It would be good that this learning should be done with ten people (minyan) that sit (settled and constant), who are busy (such as with a business) learning Torah..."
Such learning shouldn't be done only from time to time, but instead shiurim should be established and put into motion where many people attend. They should sit together and probe deeply into what redemption and Moshiach are all about.
As a result of our learning about the redemption, Moshiach, and the Beis Hamikdash, we should immediately have the privilege to see the Beis Hamikdash. Then Moshe Rabeinu will enter the Land of Israel and together we will joyfully celebrate the complete redemption.
