Beard is a gift from God, therefore why should anyone give it away by cutting it? Guru Gobind Singh, the tenth Sikh Guru, commanded the Sikhs to maintain unshorn hair, recognizing it as a necessary adornment of the body by Almighty God as well as a mandatory Article of Faith. Sikhs consider the beard to be part of the nobility and dignity of their manhood. Sikhs also refrain from cutting their hair and beards out of respect for the God-given form. Kesh, uncut hair, is one of the Five Ks, five compulsory articles of faith for a baptized Sikh. As such, a Sikh man is easily identified by his turban and uncut hair and beard.
One argument often discussed is that if you do not cut your beard, it keeps growing and will eventually reach the ground. Sikhs never cut their beard and it does not touch the ground, their eyebrows grow to a specific length, their mustaches grow to a specific length, and their beard stops at a specific length. Our body has a natural way of shedding and regenerating hair, thus after a period of time, hair seems to stay at a consistent length.
Once the beard reaches its specific length, it stops growing. If the beard in collection are cut, the body responds by growing the beard to its intended length, the beard will fall and new beard will grow to keep the hair up to the specific length for that individual. Body will always try to maintain that specific hair length for that individual may it be 12 inches, 30 inches, or 48 inches depending on the genes. It clearly indicates the link of the body with the hair all along its length. Cutting hair puts extra load on the body since the body will always try to grow the hair back to their specific length.
Sikhs do not allow to cut their beard and their beard grows to a specific length depending on their individual characteristics. Sikhs have been keeping their beard unshorn for centuries and know this fact for real.
Sikhs are not to use razors or any other such devices on their bodies from the time of birth, for they do not cut their hair from any part of their bodies. In order to keep hair neat and clean, Sikhs roll the hair on the top of their head. The hair is then covered by different types of turbans.
From the scientific point of view, keeping beard is practical because beard has many functions. It traps an insulating layer of still air just outside the skin, and thereby keeping the face cool in summer and warm in winters. Furthermore, hair absorbs harmful ultra violet radiations from the sun and reduces skin cancer. In addition, hair follicles can make androgenic hormones. Auxiliary hair provides larger surface area for evaporation of sweat. Although Sikhs do not need scientific explanations to keep hair, it is important to note that scientific explanations do indeed exist.