Leng Qie Sutra states: All living beings have been revolving in birth and death without stop from time without beginning. They have been fathers, mothers, brothers, males, females, friends and close loved ones to each other. We’ve even been birds and other animals so how could eat them?
Brahma Net Sutra states: A disciple of the Buddha must not himself kill, encourage others to kill, kill by expedient means, praise killing, rejoice at witnessing killing, or kill through mantras. He must not involve himself in the causes, conditions, methods, or karma of intentionally killing any living creature.
Brahma Net Sutra states: A disciple on the Bodhisattva path should always nurture his eternal nature of compassion and filial respect, and always devise skillful means to rescue and protect all beings. If instead, he indulges and satisfies himself to kill living beings; he commits a Bodhisattva Parajika offense.