According to Sri Shuka, there was a sage named Jamadagni who had several sons, the youngest of whom was Parashurama. Parashurama was known for destroying the line of Kshatriyas twenty-one times. King Parikshit asked why such terrible retribution was brought upon the Kshatriyas. Sri Shuka explained that the king of that territory at the time was a powerful ruler named Arjuna. Arjuna had acquired a thousand arms and many other boons after worshipping Dattatreya. He could travel all over the world through the air and none could defeat him.
Once, Arjuna came with his army to the ashrama of Jamadagni when Parashurama was away. The sage welcomed the king and his followers and began to entertain them royally with the help of Kamadhenu, the celestial wish-fulfilling cow. However, out of arrogance, Arjuna refused the sage's hospitality and left. On his return to his city, Arjuna sent some men to capture Kamadhenu and bring her to him. The men then went to the ashrama and took away Kamadhenu as well as her calf.
When Parashurama returned to the ashrama and found out what had happened, he became enraged. Taking his axe and his bow and arrows, he went out to bring back the cow and calf. Arjuna saw him coming and sent out a huge army, with elephants, horses, chariots, and foot soldiers to fight this one man. But nothing could stop Parashurama. Singlehandedly he destroyed the whole army.
Arjuna was furious and came out himself to fight. Holding five hundred bows in his thousand arms, he began showering arrows on Parashurama. But with just two arms and one bow, Parashurama destroyed all the arrows that Arjuna shot. Then Arjuna came with trees and mountains in his arms to attack Parashurama, but again Parashurama cut everything to pieces with his axe. He then cut off all Arjuna's arms and finally killed him by cutting off his head.
After seeing the destruction carried out by Parashurama, Arjuna's ten thousand sons all fled. Parashurama then found Kamadhenu and her calf and took them back to the ashrama. When he returned to the ashrama and told his father and brothers what he had done, Jamadagni scolded him, saying that he had committed a sin. Jamadagni told his son to expiate this sin by going on a pilgrimage to holy places, by practicing yoga, and by meditating on the Lord.
Years later, after Parashurama had returned from his pilgrimage, he was again out of the ashrama with his brothers one day when Arjuna's sons came there to avenge the death of their father. Seeing Jamadagni sitting in meditation, they cut off his head and carried it away with them. Even from quite a distance, Parashurama could hear his mother's cries of grief and ran back to the ashrama. Stunned and enraged at the sight of his father's body, he entrusted the body to his brothers and left with his axe to eliminate all Kshatriyas from the earth.
After twenty-one campaigns, he killed almost all of the Kshatriyas and then stopped. He then recovered the head of his father's body, placed it on the trunk, and began a great sacrifice. All the lands that he had won he gave away to the performers of the sacrifice and their assistants. At the conclusion of the sacrifice, Jamadagni returned to life and eventually became one of the saptarishis, the seven sages. Parashurama then went to practice austerities on the Mahendra mountain.