Matsyapurana 156.24

156.24

bhujagarūpaṃ saṃtyajya babhūvātha mahāsuraḥ
umārūpī chalayituṃ giriśaṃ mūḍhacetanaḥ //

Getting that boon, the Daitya considered himself immortal and afterwards in order to hide himself from Virabhadra he transformed himself into a serpent and without being noticed by Virabhadra, crawled inside where Śiva was Then, that great Asura, leaving off the disguise of the serpent, masquedered as Pârvatî in order to tempt Śiva. After making his form exquisitely alike Pârvatî by his spell he put on sharp and strong teeth, and made up his mind to kill Śiva He went near Śiva in the form of Pârvatî putting on neat dress and ornaments—21 27