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Parad Shivling when worshipped with proper procedure, belief, and enthusiasm helps human beings physically, spiritually, and psychologically. Also protects people from natural calamities, disaster, external evil effects.
Holy blessing which is obtain by performing 100 Ashwamegh Yagya, donating Lakhs of cows, donating ample of gold, and taking holy bath in all the four pilgrimage places (Char Dham) is equal to the sight (Darshan) of holy Parad Shivling.
People who worship Parad Shivling with all the good virtues, attain the blessings of Shivling present in all the 3 Loka's (Swarga Lok) and also destroys all bad sins.
Parad Shivling is Maha-Linga, also it is home to Lord Shiva's divine powers hence called "Shivalaya". It's attainment leads to prosperity and success.
Lord Siva had told to goddess Parvati that a person who worships Parad Shivling. Fear and death cannot come closer to that person, also poverty never resides at their place.