Arjuna's worship of Shiva
While the Pandavas, after defeat at dice, were living in exile in the forest, Yudhisthir thought of his weakness as compared to the strength and resources of Duryodhana, and that all the friends of their youth whose prowess on the field were known to them, were sure to devote themselves to Dronacharya. Dronacharya and his pupils, above all Karna, would fight and die not for the Pandavas, but for Duryodhana, son of Dhritarashtra, the reigning king. At that time, there came a holy man at the retreat of the brothers, and seeing the eldest Pandava in a troubled mind, and told him that there was no one in the world who could defeat Arjuna if once he received the divine and celestial weapons by doing meditation upon the high mountains.
Thus, Arjuna took vows of austerity, and promising to be turned aside by nothing that he would meet, went out for the Himalayas. When he reached the foot of the mountain, he saw a holy man sitting beneath a tree who told him that he would get any spiritual gift by him if only he asked for it. But Arjuna asked the hold man disdainfully that he had left his brothers in the forest to the south, and came there to obtain divine weapons. Thus it would not be proper for him to accept bliss and leave his brothers unaided. The holy man was none other that Lord Indra and after hearing those words from Arjuna; he blessed him and approved his resolution.
Arjuna started his meditation in the Himalayas clad in scant clothes made of grass and deer-skin and lived upon withered leaves and fallen fruits. Month after month he reduced his allowance of these till in the fourth month he was able to live on air alone, taking no other food whatever. And his head looked like lightning due to his constant bathing and purification, and he was able to stand day after day with arms upraised without support, till the earth began to smoke and the heavenly beings started to tremble from the heat of Arjuna's penance. At last, Lord Shiva, pleased with his meditation, appeared before him and blessed him with divine weapons.
Arjuna's Departure to Indraloka
After being blessed by Lord Shiva, Arjuna took leave from his brothers in the jungle and went for the Indraloka. Since Indra was Arjuna's father, he welcomed Arjuna gladly in his kingdom and asked him to stay there for some time. Arjuna got the training for the use of celestial weapons and apart from weapons training; he also made himself an expert in singing and dancing from the most beautiful apasra Urvasi. While training Arjuna in dance and music, Urvasi fell in love with the mighty Pandava and when she approached him for the same, Arjuna refused her by telling that he respected her and that she was like his mother. Thus, Urvasi cursed him to become a eunuch, but with the intervention of Indra, she relaxed her curse and made it applicable for one year in the life of Arjuna. Thus, the curse from Urvasi to Arjuna to lead the life of a eunuch for a year helped him to stay in disguise in the kingdom of Virat as Brihannala in the thirteenth year of exile.
While the Pandavas were living in exile, Jayadratha, king of Sindhu , and the husband of Duryodhana's only sister, once saw Draupadi lonely in the forest. Moved by blind passion, he tried to forcibly abduct Draupadi and wished to carry her off in his chariot with evil intentions. The Pandavas heard the lamenting voice of Draupadi for help and Arjuna, with his shower of arrows checked the movement of Jayadratha from all directions. Then Bhimaeven tried to kill the offender then, but Yudhisthir forgave him since he was the husband of their cousin Duryodhana's only sister and if they killed him then their sister would become a widow. They let Jayadratha to leave the place and Arjuna vowed to kill him in the battle.
In this Parva, while the Pandavas were sitting in a very melancholic mood and Yudhisthir was thinking himself to be the most unfortunate person in the world who was deprived of his position and power and was left in the jungle with his brothers and wife. At that time came Rishi Vrihadaswa and when he came to know about the mental state of Yudhisthir, he narrated to him the tale of the king of Nishadas, called Virasena who had a son named Nala. The king was dishonestly defeated by Pushkara, and thus he stayed in the woods with his spouse. Then he went on to narrate the tale of the king and his son Nala who got married to the beautiful Damayanti. Thus, the rishi compared the state of Yudhisthir to that of the king of Nishadhas and told him that while Virasena dwelt in the forest without any attendants or maids or servants and was accompanied by his wife and his son Nala, Yudhisthir stayed surrounded by his heroic brothers and with the blessing of Lord Krishna, the creator of the universe. With the end of the Van Parva, starts the narration of the Virata Parva of Mahabharata.