Patanjali in the yoga sutras advises that future suffering should be avoided. He gives the method of ahimsa don't cause the suffering of any other being.The benefit is that you will be free from suffering. Patanjali offers a different view point from the practice of non-violence. The opposite of ahimsa is himsa, violence or harm. There are three ways to cause harm;
Physical by hurting someones physical body
Vocal; by speaking against others, hurting their feelings
Mental; by thinking against others.
"By physical injury one can destroy physical forms. By vocal injury one can destroy both physical and mental forms. By mental injury one can destroy even the form of spirit". Shri Brahmananda Sarasvati.
In Patanjali's ashtanga yoga system, ahimsa is the first yama or restraint. It is recommended for how you should restrain you're behaviour toward others. The second limb of the ashtanga yoga system is niyama; observances. Patanjali clearly classifies ahimsa as a yama not niyama.
Ultimate happiness is achieving kindness, being considerate of others.
"Who will be the happiest person? The one who brings happiness to others" Swami Satchidananda