In the Nala-Damayanti story narrated by sage Vrihadaswa to Yudhishthira, there's mention of the Naga, Karkotaka, who bites and disfigures Nala for his own good.
But what's the story of Karkotaka deceiving sage Narada? Why did he deceive Narada?
King Nala saw a mighty conflagration that was raging in that dense forest. And in the midst of that conflagration, he heard the voice of some creature, repeatedly crying aloud, 'O righteous Nala, come hither.' And answering, 'Fear not,' he entered into the midst of the fire and beheld a mighty Naga lying in coils. And the Naga with joined hands, and trembling, spake unto Nala, saying, 'O king, that I am a snake, Karkotaka by name. I had deceived the great Rishi Narada of high ascetic merit, and by him have I been cursed in wrath, O king of men, even in words such as these: 'Stay thou here like an immobile thing, until one Nala taketh thee hence. And, indeed, on the spot to which he will carry thee, there shalt thou he freed from my curse. It is for that curse of his that I am unable to stir one step. I will instruct thee in respect of thy welfare. It behoveth thee to deliver me. I will be thy friend. There is no snake equal to me. I will be light in thy hands. Taking me up, do thou speedily go hence.' Having said this, that prince of snakes became as small as the thumb. And taking him up, Nala went to a spot free from fire.
