Vaishampayana narrates the conclusion of the Khandava burning
The Khandava forest is gone, consumed by Agni after five days and a night of burning. The fire, drunk on rivers of fat and marrow, appears before Arjuna and Krishna, satisfied. Then Indra himself descends, surrounded by the Maruts, and offers the heroes a reward for a deed even gods would find difficult.
The fire had done its work. For five days and a night, Agni, the god of fire, had consumed the Khandava forest with the relentless assistance of Arjuna and Krishna. He drank rivers of fat and marrow, bringing terror to every living thing within the woods. Now, utterly satiated, the fire appeared before the two warriors, his form radiant with contentment.
Then the sky filled with a greater presence. Surrounded by masses of Maruts (storm gods), the illustrious lord of the gods, Indra, descended. He spoke to Partha (Arjuna) and Madhava (Krishna). “You have accomplished a feat that is difficult, even for the immortals,” he said. “I am pleased. Choose boons that are difficult to obtain and beyond what humans can get.”
Arjuna asked first. He wanted all of Shakra’s (Indra’s) divine weapons. Indra agreed, but fixed a condition. “O Pandava! When the illustrious Mahadeva (Shiva) will be pleased with you, that is when I will give you all the weapons. I will myself know when that time has arrived. Because of your great asceticism, I will then bestow on you all my agneya weapons and all my vayavya weapons and all my other weapons, and you will accept them.”
Krishna’s request was different. He asked for a boon of enduring, unwavering friendship — that he might always be loving towards Arjuna. The lord of the gods happily granted it. Having bestowed these promises, Indra took his leave of the still-burning Agni and returned to heaven with the thirty gods.
The fire, having consumed the forest with every animal and bird within it, was finally full. He ceased his burning. Flesh eaten, fat and blood drunk, he was filled with extreme joy. He spoke to the heroes who had made his feast possible. “O warriors! O tigers among men! You have gratified me to the point of extreme bliss. You now have my leave to go where you want.”
Thus granted leave by the great-souled fire, the three — Arjuna, Vasudeva (Krishna), and the danava (demon architect) Maya, who had been rescued from the flames — wandered for a time. Their journey ended on the banks of a beautiful river, where they seated themselves to rest.