Kashyapa Muni had two wives, Kadru and Vinita. Kadru was the mother of snakes and Vineeta was mother of Garuda. Once upon a time, upon seeing the horse plowing in the chariot of Lord Surya, Kadru said to Vineet, “sister ,According to you, what color is this horse plowing in the chariot of the sun?” Vineet says sister, I think this horse is white in color. Vinita says sister, according to you what is the color of this horse. Kadru said, according to me, this horse is black in color. Kadru says that both of us should bet, if according to you this horse will be of white color then I will become your maid and if it is black then you become my maid. Vineeta accepted that bet.
Kadru had many small snakes that were black in color. She ordered his sons that they go and cling to the body of the horse, plowing in the Chariot of the sun, which made it look black. The sons who refused to obey Kadru, she cursed her serpent sons that you should fall into the fire of Janamejaya’s sacrificial fire. Now both Kadru and Vineeta went to see that horse of the sun together, then they saw that the horse is black in color. Vinita lost the bet, making her very sad.
Seeing his mother Vineeta unhappy, Garudji came there and said, “Mother, tell me what kind of sorrow you have, I will try to remove that sorrow right now.” The life of a son who does not try to remove his mother’s misery is meaningless. Hearing the words of the son, Vinita said, “Son, I have become the maid of my sister Kadru.” She wants me to carry her on her shoulder. So Garuda said, mother, don’t worry, I will carry Kadru on my back. Saying this, Garuda lifted Kadru on his pit and started going across the sea, then he asked very politely, tell me the solution to get rid of from my mother being your handmaid.
She said ,you bring nectar from heaven for my sons. This will definitely free your mother from being my maid. Then Garudji went to heaven and after fighting with Indra brought the urn of nectar to Kadruji. At that time, all the snakes went to bathe before drinking the nectar. At the same time, Indra came and stole the urn of nectar and the snakes saw the grass there and started licking it, so that they became living beings with slit tounge.
It was at that time that there was a monk named Zartkaru, he was very knowledgeable of the Vedas. He did not get married and used to travel on earth alone. He once found the spirits of his ancestors imprisoned in a cave in the forest. His ancestors said, son, get married, so that we will get freedom from this terrible cave. Then Jartkaru said that if I get a wife of my name, I will definitely marry her. Having said this, he left from there and started wandering on Earth freely.
Kadru’s ,sons ,like vasuki etc who refused to listen her, were cursed by her thay ,they will fall into the sacrificial fire of janmejay, all these serpents went to Brahmaji and asked him how to avoid the curse. Then Brahma Ji said that ,Vasuki there is a great sage named Zartkaru, you give your sister named Zartkaru to him as his wife. The son born from these two will protect you. The name of that son of Zartkaru will be a aastik, he will be a very godly and great man who knows the Vedas.
On getting Brahma’s orders, Vasuki got his sister named Jartkaru married to Jartkaru Muni. From whom great sage named Aastika was born. He was the one who saved all the snakes from being consumed by the curse of Kadru in the yagya of Janamejaya. In order to protect the clan of his mother, he did this work on the prayer of Takshak Nag.