Hinsa, or violence, is considered to be one of the greatest sins in Hinduism and for this there is no forgiving. Hinsa in any form, be it physical harm to any living being, or mental and emotional harm to anyone, human or animal, is considered sinful.
The principle of ahimsa, or non-violence, is deeply ingrained in Hindu traditions and teaching and all Hindu gurus and intellectuals have preached the policy of ahimsa. Acts such as killing, injuring, or even speaking harshly to others are considered grave sins that can have bad effects on someone’s karma.