Moshe Rabbeinu noticed one day that a lamb had run away from the flock. He ran after it in order to bring it back. From this we can learn how meaningful every Jew is in the eyes of Moshe Rabbeinu, even if he is a Jew who has run away from the flock....
And since “the first redeemer is also the last redeemer,” it is clear that what is true of Moshe Rabbeinu is likewise true of Moshiach — every Jew, wherever he may be, is precious. Moreover, if Moshe Rabbeinu acted in this spirit even before the Giving of the Torah, how much more so should one act in this spirit after the Giving of the Torah, for this was the time at which, “You chose us from among all the nations.”
(the Rebbe, reprinted from Exile to Redemption, with perm. from Sichos in English)