Him I call indeed a Brâhmana who finds no fault with other beings, whether feeble or strong, and does not kill nor cause slaughter.
Nidhāya daṇḍaṁ bhūtesu, tasesu thāvaresu ca; Yo na hanti na ghāteti, tamahaṁ brūmi brāhmaṇaṁ.
Dhammapada 405
The same idea in other traditions
Thou shalt not muzzle the ox when he treadeth out the corn.
The Master angled,—but did not use a net. He shot,—but not at birds perching.
A righteous man regardeth the life of his beast; But the tender mercies of the wicked are cruel.
One who does not frighten anyone, and who is not afraid of anyone else - says Nanak, listen, mind: call him spiritually wise.
"He who thoroughly knows living beings, whether they move or not, and does not injure them in any of the three ways, him we call a Brâhmana.
He through whom the world is not agitated, and who is not agitated by the world, who is free from joy and anger and fear and agitation, he too is dear to me.
There is not an animal (that lives) on the earth, nor a being that flies on its wings, but (forms part of) communities like you. Nothing have we omitted from the Book, and they (all) shall be gathered to their Lord in the end.
In a desert a man found a dog that was dying from thirst. Using his hat as a bucket, he fetched water from a well and gave it to the helpless animal. The prophet of the time stated that God had forgiven the man his sins because of his kindly act. Reflect, if thou be a tyrant, and make a profession of benevolence. He who shows kindness to a dog will not do less towards the good among his fellows. …