The Curse of the Kumaras: Origin of Vishnu's Avatars

This scene at Vaikunth forms the backstory behind four of Vishnu's avatars: Varah (Boar), Narasimha (Man-Lion), Ram, and Krishna.

Jay and Vijay were closely guarding the gates of Vaikunth (literally, "place of eternal bliss"), the abode of Lord Vishnu and Goddess Lakshmi. They were astonished to see four young boys approaching the gate.

"Stop right there and identify yourselves," Jay commanded.

"We are the Four Kumaras," the boys cried in unison.
"I am Sanak," said the first boy.
"I am Sanandan," said the second.
"I am Sanatan," said the third.
"And I am Sanatkumar," said the fourth.

"Why are you here? What do you want?" asked Vijay.

"We want to see Lord Vishnu," said one of the boys.

"You cannot see Lord Vishnu now, as he is resting," said Jay.

"Lord Vishnu never rests," said another boy. "If he did, the universe would cease to function."

"We have come a long way to see Lord Vishnu," said the third boy. "Please let us in."

"No," said Vijay firmly.

"You have misused your position as gatekeepers of Vaikunth and denied us entry," said the fourth boy. "We hereby curse you: you will be born as demons on Earth three times."

Just then, Vishnu emerged from his chamber and arrived at the gate after hearing the commotion.

"These boys just cursed us for doing our jobs," Jay and Vijay complained to Vishnu.

"Your job is not to become a barrier between my devotees and me," Vishnu said. "You have committed a grave error and deserve to be punished."

Vishnu then turned to the Kumaras.
"How long will Jay and Vijay have to suffer this curse?" he asked.

"They will live as demons until your avatar kills them in each life," replied one Kumar.

Thus, in the Satya era, Jay and Vijay were born as the demons Hiranyakashyap and Hiranyaksh, respectively. In the Treta era, they were born as the demons Ravan and Kumbhakarn. In the Dvapar era, they were born as the demons Shishupal and Dantavakra. Each time, they were slain by an avatar of Vishnu, finally freeing them from the Kumaras' curse.