Mbh 3.180.8a

“Yudhishthira said, ‘O most intelligent one, you have fine intelligence and you know all that is fit to be known. Why do you ask me that question? You knew all and you performed such wonderful deeds and you lived in heaven. How could then illusion overpower you? Great is my doubt on this point.’ The snake replied, ‘Prosperity intoxicates even the wise and valiant men. Those who live in luxury, (soon) lose their reason. So, I too, O Yudhishthira, overpowered by the infatuation of prosperity, have fallen from my high state and having recovered my self-consciousness, am enlightening thee thus! O victorious king, thou hast done me a good turn. By conversing with thy pious self, my painful curse has been expiated. In days of yore, while I used to sojourn in heaven in a celestial chariot, revelling in my pride, I did not think of anything else, I used to exact tribute from Brahmarshis, Devas, Yakshas, Gandharvas, Rakshasas, Pannagas and all other dwellers of the three worlds. O lord of earth, such was the spell of my eyes, that on whatever creature, I fixed them, I instantly destroyed his power. Thousands of Brahmarshis used to draw my chariot. The delinquency, O king, was the cause of my fall from my high prosperity. Among them, Agastya was one day drawing my conveyance, and my feet came in contact with his body; Agastya then pronounced (this curse) on me, in anger, ‘Ruin seize thee, do thou become a snake.’ So, losing my glory, I fell down from that excellent car and while falling, I beheld myself turned into a snake, with head downwards. I thus implored that Brahmana, ‘May this curse be extinguished, O adorable one! You ought to forgive one who has been so foolish from infatuation.’ Then he kindly told me this, as I was being hurled down (from heaven), “The virtuous king Yudhishthira will save thee from this curse, and when, O king, horrible sin of pride will be extinguished in thee; thou shalt attain salvation.’