Sivalinga of Vaidyanath is a gift of Lord Maheswar and it was granted after
vigorous penance and exhibition of deep faith and devotion to him by
Ravanabrahma. According to Kotirudra Samhita, Ravana desired to make Lankarajya
invincible and the danava race immortal. He knew that Maheswar alone could bless
him with the fulfillment of his desires and he alone would be easily won over by
penance and prayers. Accordingly he went to Kailas and started penance. When it
could not yield the desired, he began cutting his heads one after another and
throwing them into agnikund as oblation. Without remorse nor expression of
anguish, his persistence went on till he offered nice heads. Before severing the
tenth, the Lord appeared and said, "I am indeed pleased with your devotion,
ask anything and it will be granted onon". Waiting only for this, he asked
for the Atmalingam that could ensure immortality to the adorers and
invincibility to the place of its occupation. Lord Maheswar, the
Omnicompassionate without forethought or insight granted it on the spot.
Together with it, pitying at the loss of nine heads, he restored them. And so,
once again he became Dasakantah - ten-headed Ravana.