The Rebbe's guidance on the beard and on a distinctive Jewish appearance:
The halachah. Removing the beard with a razor is strictly forbidden by Torah law (IK 2332), and the Rebbe analyzed at length the laws of shaving with scissors and other methods and their sources (IK 003, 004, 5054). Not shaving the corners of the beard follows both halachah and chassidic custom (IK 8297), and according to chassidic tradition the beard should not be trimmed or altered (IK 7603, 7235). Distinctive Jewish dress is itself a real halachic obligation (IK 7730).
Its meaning. The beard has deep spiritual significance in both halachah and Kabbalah (IK 8662), reflects yiras Shamayim and the Divine image (IK 1254, 1791), and guarding it draws down Divine blessing (IK 6469). A spiritual leader should visibly uphold this standard rather than conform (IK 2871), and a yeshiva may make it part of its standards (IK 2109).
Livelihood, shidduchim and family. A beard does not harm one's livelihood or shidduch prospects — it brings blessing (IK 1254, 3323, 3359). Parents should support a son's sincere decision to grow a beard, and parental authority does not override Torah law here (IK 2893, 8577); parental pressure against it can itself harm opportunities (IK 3359). In a shidduch, Torah values should come before social pressure (IK 9041), and a demand to shave before a wedding should be firmly rejected (IK 9001). Explain the beard's significance to one's wife, and a wife should support her husband's spiritual growth (IK 7117, 9706). Pursue it with confidence even in the face of criticism (IK 6845); each person's situation should be considered individually (IK 8030).
See also: Mitzvos in daily life – Tznius and head covering; Shidduchim – What to look for.