Since his youth, Karna was more interested in the art of warfare than in driving a chariot like his father Adhiratha. Karna and his father Adhiratha met Acharya Dronacharya, who was one of the best masters of the art of warfare at that time. Dronacharya used to give education to the Kuru princes at that time. He refused to teach Karna, because Karna was the son of a charioteer and Dronacharya used to teach only Kshatriyas.
After Dronacharya’s disagreement, Karna contacted Parashurama, who used to teach only Brahmins. Calling himself a Brahmin, Karna requested Parshuram for education. Parshuram accepted Karna’s request and trained Karna in the art of warfare and archery like himself.
Karna was cursed by his Guru Parshuram and Mother Earth. Karna’s education was at its last stage. It is a matter of afternoon, Guru Parshuram was resting with his head on Karna’s thigh. After some time, a scorpion came from somewhere and started biting Karna’s other thigh and making a wound. Karna did not want at all that there should be any obstacle in the rest of his Guru. That’s why he didn’t remove that scorpion and throw it away. That scorpion kept giving severe pain to Karna with its sting, but Karna did not let his teacher’s rest be disturbed.
After some time when Guru Parshuram’s sleep broke and he saw that a lot of blood was flowing from Karna’s thigh. He said that only a Kshatriya can have the fortitude to bear the sting of a scorpion, not a Brahmin, and Parashurama cursed him for his false speech- “Whenever Karna gets the most of his teachings, It will be of no use to him on that day when he will need it.
Karna, who himself did not know to which lineage he belonged, apologized to his guru and said that if any other disciple had been in his place, he would have done the same. Although Parshuram felt very guilty for cursing Karna out of anger, he could not take back his curse. Then he gave Karna his bow called ‘Victory’ and also blessed him that he would get the thing he wanted most – “unfading fame.”
In some folktales, it is also believed that Lord Indra himself in the form of a scorpion tormented Karna because he wanted to reveal his true Kshatriya identity to Parashurama. After leaving Parshuram’s hermitage, Karna wandered for some time. During this, he was learning the art of ‘shabdbhedi’. During the practice, he mistook a cow’s calf for a wild animal and shot an arrow at it and the calf was killed. Then the Brahmin, the owner of that cow, cursed Karna that- “Just as he has killed a helpless animal, he too will be killed one day, when he will be most helpless and when all his attention is on something other than his enemy. And will be at work.”