SB 4.11.7
manur uvaca
alam vatsatirosena
tamo-dvarena papmana
yena punya-janan etan
avadhis tvam anagasah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Lord Manu said: My dear son, please stop. It is not good to become unnecessarily angry — it is the path to hellish life. Now you are going beyond the limit by killing Yaksas who are actually not offenders.
Purportby His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In this verse the word atirosena means “with unnecessary anger.” When Dhruva Maharaja went beyond the limits of necessary anger, his grandfather, Svayambhuva Manu, immediately came to protect him from further sinful action. From this we can understand that killing is not bad, but when killing is done unnecessarily or when an offenseless person is killed, such killing opens the path to hell. Dhruva Maharaja was saved from such sinful action because he was a great devotee.
A ksatriya is allowed to kill only for maintenance of the law and order of the state; he is not allowed to kill or commit violence without reason. Violence is certainly a path leading to a hellish condition of life, but it is also required for maintenance of the law and order of the state. Here Lord Manu prohibited Dhruva Maharaja from killing the Yaksas because only one of them was punishable for killing his brother, Uttama; not all of the Yaksa citizens were punishable. We find in modern warfare, however, that attacks are made upon innocent citizens who are without fault. According to the law of Manu, such warfare is a most sinful activity. Furthermore, at the present moment civilized nations are unnecessarily maintaining many slaughterhouses for killing innocent animals. When a nation is attacked by its enemies, the wholesale slaughter of the citizens should be taken as a reaction to their own sinful activities. That is nature’s law.