Arjuna Trained by Indra and Chitrasena
Arjuna arrives in Indra's celestial abode and is welcomed by gods and gandharvas with full honors. He lives in his father's house, learns all the great weapons and how to withdraw them, and receives Indra's own vajra weapon — a gift that makes a sound like thunder and lightning. Then Indra gives him to Chitrasena to learn the singing and dancing of the gods, a skill unknown among men that will serve him well.
Arjuna arrived in the abode of his father, Indra, king of the gods. The gods and the gandharvas (celestial musicians) knew Shakra's mind — they welcomed Partha with a supreme arghya (offering of honor). They offered him padya (water for washing the feet) and achamaniya (water for sipping), and guided him to the entrance of Purandara's dwelling.
Having been shown such homage, Jishnu — the conqueror of enemies — lived in his father's house.
There, Pandava learned about all the great weapons and the means of withdrawing them. From Shakra's own hands, he received the vajra weapon — Indra's beloved thunderbolt, impossible to withstand. When he received it, the weapon made a great roar, like lightning, marked by the signs of clouds and peacocks.
On receiving the weapon, Pandava Kounteya thought of his brothers, still wandering in the forest. But on Purandara's instructions, he lived there happily for five years.
When Partha became skilled in the use of all weapons and the right time had come, Shakra told him: "O Kounteya! Now learn singing and dancing from Chitrasena. Learn the music that is only known to the gods and is unknown in the world of men. O Kounteya! If you learn this, it will bring your own welfare."
Purandara then gave him to Chitrasena as a friend. Partha lived happily with him, free from all disease. Aranyaka Parva, Chapter 342