Bhagavad Gita
A story within the ancient Indian epic the Mahabharata in which Arjuna, a member of the warrior class is face with the moral conflict of killing his relatives in order to fulfill his duties. The story is in the form of dialogue between Arjuna and Krishna, a manifestation of Vishnu the preserver.
Vishnu explains that, according to Arjuna's Varna Duty (class duty) in relation to the concepts of the gunas, it is more immoral to run away than to fight. This is because Arjuna must fulfill his varna duty and, according to the concepts of the gunas, Arjuna is not the one fighting. The gunas, being the movers of Arjuna's body, are the ones responsible for all actions.
Since everything comes of Brahman, to kill another is not taking anything away from them for they will return to Brahman or be manifest into another body