Gods Send Nala as Messenger to Damayanti
Four gods — Indra, Agni, Varuna, and Yama — desire Damayanti and choose Nala to deliver their proposal. Nala has already promised to do their bidding, but when he learns the task, he protests: he himself desires Damayanti. The gods insist he keep his word.
Brihadashva told Yudhishthira the story of Nala.
Nala gave his promise to the four beings who had appeared before him — he would do whatever they asked. Then he joined his hands in salutation and asked them: "Who are you? Who desires that I should be his messenger? What is the task that I am required to perform? Tell me in detail."
Thus addressed by the king of Nishadha, Maghavan — Indra himself — replied. "Know that we are the immortals and that we have come here for Damayanti's sake. I am Indra. This is Agni. This is the lord of the waters. O king! This is Yama, who brings an end to human bodies. Go and tell Damayanti that the lokapalas (guardians of the world), together with Indra, are arriving with a desire to see her. The gods Shakra, Agni, Varuna and Yama wish to obtain her. She should choose one of these gods for her husband."
Thus addressed by Shakra, Nala joined his hands in salutation and requested them not to send him for this purpose — because he had the same objective. He too desired Damayanti.
The gods replied: "O Nishadha! You have already promised to do our bidding. O Nishadha! How can you then fail to do what we ask? Go immediately."
Thus addressed by the gods, Nishadha again replied: "How can I enter a palace that is guarded so well?"
Shakra told him that he would be able to enter.
Having been thus addressed, Nala went to Damayanti's residence. Aranyaka Parva, Chapter 349