NON-VIOLENCE     [rnam par mi 'tshe]
What is non-violence? It is an attitude of loving kindness belonging to non-hatred. Its function is not to be malicious.
Non-violence is patient acceptance which expresses itself in the sentiment of how wonderful it would be if suffering sentient beings could be released from all their frustrations. Patient acceptance is an attitude not marred by the slightest idea of inflicting suffering.

This non-violence and the rejection of harming others is the central idea of the Buddha's teaching. It has been explained as follows (in the Vinaya):

True patient acceptance -- patient acceptance difficult to attain --
Has been said to be real nirvana by the Buddha.
A monk who harms another and who acts violently
Towards another is not a religious person.
To fulfill the vinaya, it is necessary to carry about a water strainer in order to avoid harming life in water. Since a person who does not carry a water strainer is one who goes against loving kindness taught by the Buddha, he must be uprooted from his foundation of harming another and be earnestly advised of the need to actualize the four attitudes by which one becomes an ascetic, namely,
1.    Even if one is reviled, he should not revile in return.
2.    Even if one is angered, he should not retaliate with anger.
3.    Even if one is struck, he should not strike back.
4.    Even if someone pries into one's affair, he should not pry into someone else's affair.
Therefore, when those who have insight truly understand these four attitudes, they will necessarily conclude that the renuciation of violence is the quintessence of the teaching.