Why Parashuram killed his mother and his brothers? Parashuram/Parashurama is the Avatar of Lord Vishnu who killed his mother, Renuka, and his brothers.
Parashurama (or Parshuram) is said to be the sixth avatar (incarnation) of Lord Vishnu. Parashuram is the only Vishnu avatar who is said to be immortal. He never returns to abstract Vishnu. He is the only Vishnu avatar that co-exists with other avatars of Lord Vishnu namely Rama and Krishna in some versions of Ramayana and Mahabharata.
Birth of Parashuram:
It is said that in Dvapara Yuga (or Dwapara Yuga), Vishnu descends as Parashuram to restore the order as the kings have abandoned dharma (righteousness) in their quest for power and are blinded with passion and ignorance.
Parashurama was born to sage Jamadagni and his wife, Renuka. He was their fifth son. Parashurama is also known as Rama Jamadagnya and Rama Bhargava.
Even though he was born in the family of a sage, he chooses to become a warrior to fight and destroy evil kings who abuse their military strength for their gains.
He even kills his mother for being unfaithful to his father and his brothers for disobeying their father.
Parashuram killed his mother Renuka and his brothers:
According to Bhagavata Purana, the story goes like this.
One day, when Renuka (his mother) went to the bank of Ganges to fetch some water. There she saw the king of the Gandharvas (Citraratha), garlanded with lotus flowers along with the Apsaras (celestial women). She was slightly drawn to Citraratha and forgot that the time for the fire sacrifice was passing.
After realizing that time for the fire sacrifice had passed, she stood with folded hands before sage Jamadagni as she afraid of being cursed by the sage. Jamadagni learned that why she has forgotten the time through his meditative powers and became enraged.
He said, ‘Remove her my sons, she’s full of sin.’
His four eldest sons refused to do so as killing a woman, and that to their mother was a great sin. But at the same time, not obeying the orders of an elder, especially their father’s is also a great offense.
Jamadagni then ordered Parashurama to do the same. Parashurama, who was fully aware of the prowess of his father, who was practiced meditation and austerity, obeyed his father without any question.
He terminated his mother and all his brothers.
Jamadagni was pleased with the obedience of his son and asked him what benediction (blessing or boon) he would like. Parashurama said, ‘Let my mother and brothers live again and not remember having been killed by me. This is the benediction I ask.‘
His father grants him the boon. His mother and brothers came alive and were very happy as if they had awakened from a deep sleep. Parashurama obeyed his father because he already knew of his father’s power.
Source: Śrīmad-Bhāgavatam (Bhāgavata Purāṇa) 9.16.2 – 9.16.8