In Skanda Puranam, Vishnav Khand chapter, Sage Sutji narrated an incidence of sage Kashyap and King Parikshit story to all the sages.
Dead snake wrapped around sage Shamik’s neck
Once there was a King named Pareekshit who ruled Hastinapur. one day he went to forest for Hunting and attacked the deer with his arrow but the deer dissapeared. Searching for the deer he went into the forest where he found sage Shamik doing penence. King Pareekshit asked the sage if he saw an injured deer. Since Sage Shamik is in penance he dint respond. King Pareekshit got angry for not replying and wrapped a dead snake around sage Shamik neck and went off.
Shringi curses King Parikshit
Later sage shamik’s son Shringi saw the dead snake around his father’s neck. Shringi then cursed the one who insulted his father by wrapping the dead sanke around his neck would not see the seventh day as thaksak nag(poisnous snake) would bite them to death.
Sage shamik after knowing the truth, sent a deciple named “Daurmukh” to inform the king about the curse so he can take preventive measures.
So King parikshit built a hut in the middle of Ganges river and started living there as instructed by “Daurmukh”.
Sage Kashyap’s attempt to save King Parikshit
Sage Kashyap came to know about the curse and he knew the antidote for the Thaksak snake bite. Soon sage Kashyap proceeded towards King Pareekshit expecting some reward for helping King Pareekshit. Thaksak snake disguised himself as a Brahmin and asked sage Kashyap the reason behind the meeting of King Pareekshit. Sage kashyap revealed his intention. Soon Thaksak snake bit the huge tree where a man was sitting on that tree. That tree and the man both collapsed. Then Sage Kashyap gave life to both of them with his medicine.
Seeing this Thaksak asked Kashyap how much he is expecting from the king when king comes alive after King’s snake bite. Then Thaksak gave him the wealth more that what he is expecting and managed him to go back to his home.
Thaksak snake kills King parikshit
Thaksak then asked other serpents to go to the place where the King Parikshit was staying. So many serpents disguised themselves as hermits and went to King Parikshit with some fruits and offered to him. Thakshak had hidden himself in palm fruit among those fruits and killed the King Pareekshit to death. Janmeya was made the next King. People around the kingdom started critisizing the sage Kashyap as he was unable to save King Parikshit. Then sage Kashyap decided to go to Pilligrimage to Venkatachaleshwar to get liberate from his sin.