Pashupatastra to Arjuna
In the Vana Parva section of the Mahabharata, there is the story of how Arjuna received the mighty Pashupatastra weapon from Lord Shiva. After Yudhishthira's defeat in the gambling contest, the Kauravas exiled the Pandava brothers in the forest. While they were living in the forest, Arjuna was instructed by the Lord of Heaven, Indra, to perform austerities for propitiating Shiva. Arjuna left his brothers and Draupadi, and went to another part of the forest to perform his austerities.
Shiva was pleased with Arjuna’s prayers. When a demon called Muka who had the form of a wild boar attacked Arjuna, Shiva appeared in the form of a hunter called Kirata. Arjuna and Kirata simultaneously shot their arrows at Muka. Struck by their arrows, the demon was instantly killed. The demon’s death led to an argument between Arjuna and Kirata over whose arrow had killed Muka. A battle broke out between them. Arjuna was amazed to find that he was unable to vanquish the hunter. Finally it dawned on him that the hunter was the same God that he was trying to propitiate, Shiva. He surrendered himself to Shiva, who blessed him and granted him the Pashupatastra weapon.
The story of the battle between Arjuna and Shiva (in the form of Kirata) has been retold in the epic poem called Kiratarjuniya, by the poet Bharavi, who probably thrived in the sixth century BCE, or before that. The epic poem consists of sixteen cantos and is regarded as a great Sanskrit classic. It is known for its decorative composition, brevity, and elaborate similes and metaphors.