Hindus wear their sect's religious symbol on their foreheads.
The symbol is of two types.
One is 'Vibhuti, also called 'Thiruneeru' and another is' Nama' (Thiruman).
Vibhuti is applied to the forehead by those who worship Shiva and Nama or Thiruman by the worshipers of Vishnu, .
The Smritis insist on one wearing either of these; failure will result in spiritual non development.
Vedic scriptures say,
"Lalaata Shoonyam Smashaana Tulyam",which means that "an empty forehead is comparable to a cemetery.
The great saint Thiru Gyaana Sambandar did many wonders with Vibhuthi and he expounds the greatness of Vibhuti in one of his Pathigams called "Thiruneetru Pathigam" as follows,
Mandhira maavadhu neeru| Vaanavar meeladhu neeru ||
Sundhara maavadhu neeru |Thudhikkap paduvadhu neeru ||
Thandhira maavadhu neeru| Chamayaththil ullaadhu neeru ||
Senthuvar vaayumai pangan|Thiruaalavaayaan Thiruneerae ||
Vibhuti.
The term Vibhuti means , in general, greatness, and here it means the Sacred Ash as well.
The Bhagavad Gita has a Chapter called The Vibhuti Yoga(Chapter 10) where Lord Krishna speaks of His various manifestations, including His Universal Form, Virat Roopa'
Therefore the Chapter is called the Vibhuti Yoga.
How come this Sacred Ash is reckoned to be Great?
In Life, Hinduism asserts, that one should be humble and remember his status, that is of his Mortality.
Accepting Mortality wholeheartedly calls for great effort, and once you accept this, you would not behave in such a way that hurts others.
Because the Vibhuti represents the Ashes one's Body is turned into after death, the applying of Vibhuti reminds one constantly of his mortality.
The acceptance of this fact and consequent sober behavior speaks of greatness.
Hence Vibhuti is called as such.
In Sanskrit, Bhoothi means Aishwaryam, meaning wealth, treasure, precious. Vi-bhoothi with an Upasarga (preposition "vi") means very or more valuable. The synonyms of Vibhuhti in Sanskrit as said in the Amara-kosha is "Vibhuthi: bhoothi: Aishwaryam".Vibhuhti can also be called as Bhoothi,Aishwaryam,Basma.
Legends and Purana have it that Lord Rudra( as distinct from Lord Shiva) Resides in the Smasana, where the bodies are cremated.
The Hindu custom is that once one dies, the body must be kept at Home for a period of ,minimum 3 nazhikais or approximately one and a half hours before the Death ceremonies begin(One Nazhikai-24 minutes, Two and a Half Nazhikais, one hour).
The ceremonies at Home shall take about an hour and a half.
Travel to burning Ghat an hour,ceremony at the Ghat an hour, that makes about five hours from the time of Death to lighting the Pyre.
The chances of the Death not being final is guaranteed during this period , as the body is not to be set afire before this period.
Rudra is the Deity of Destruction, destroys only to enable for its reappearance -Thirodhana (Concealment), an Attribute of Lord Shiva, the others being,Srusti as Brahma, Stithi as Vishnu,Samhara, as Rudra,Thirodhana and Anugraha as Shiva.(Concealment and Grace).
As Rudra is the ruling Deity of Death,Vibhuti is applied.
