"Even the Bird has Found a Home"
"Even the bird has found a home, and the swallow a nest for herself!"
The particular care of Divine Providence extends even to seeing to it that a creature as small as a bird should find a home. And even the swallow, which is constantly on the wing and has no fixed home, has at least a nest. The only son of the King of kings, however, has neither home nor nest, neither a permanent nor a temporary home: he is a restless wanderer in exile.
Hence the pained cry that erupts from every heart: "Ad masai? How much longer?"
From a talk of the Rebbe on Shabbos Parshas Ki Sissa, 5747 
Self-Sacrifice for Mashiach
In a recently republished letter, the author of Minchas Elazar [R. Elazar Chaim of Munkatch] writes explicitly and unequivocally that one is obliged to be prepared to sacrifice one's life for the sake of the coming of Mashiach, just as one is obliged to undergo mesirus nefesh rather than transgress any one of the three prohibitions concerning which our Sages ruled, "Rather be killed than transgress."
From a talk of the Rebbe on Shabbos Parshas Mikeitz, 5744 
A Life-Threatening Danger
It is an unquestioned principle in Torah law that the saving of a life overrules all the commandments of the Torah (except for three).
Now, we are going through an extremely difficult period, when the very survival of the spiritual life of Jews is constantly threatened by intermarriage and assimilation. Accordingly, G-d is obliged to liberate His people from this exile, without detaining them for one moment longer -- for spiritually, this is a life-saving emergency!
From a talk of the Rebbe on Shabbos Parshas Mishpatim, 5745 
A Jewish Bondman
Our Sages teach, "If one acquires a Jewish bondman, it is as if he acquired a master over himself."
Since he serves G-d, every Jew may be regarded as a "Jewish bondman." G-d is thus obliged not only to supply him with all his material and spiritual needs, but in addition, He is obliged to respond to the pleas of His people that they can no longer tolerate this exile.
And our Sages have taught, "A tzaddik decrees..." ("and your people are all tzaddikim") "...and G-d fulfills."
From a talk of the Rebbe on Shabbos Parshas Yisro, 5745 
Striking One's Son
The Torah rules that it is forbidden to strike one's grown son.
How much more must this be forbidden when we are speaking of all the Children of Israel, who ever since the Exodus from Egypt and the Giving of the Torah have been "a great ('fully-grown') nation."
Yet despite all this, this exile has continued for over 1900 years!
From a talk of the Rebbe Shlita on Shabbos Parshas Tzav, 5742 
2. In Igros Shapirin, p. 238ff.
3. Sanhedrin 74a.
4. Rambam, Hilchos Yesodei HaTorah 5:1.
5. Kiddushin 20a, where the Sages stipulate that an employer is obliged by Torah law to provide his bondman (eved Ivri) with better wine and bread and a more comfortable mattress, than his own.
6. Cf. Taanis 23a.
7. Yeshayahu 60:21.
8. Shulchan Aruch, Yoreh Deah 240:20.
9. Devarim 4:7