In the Mahaparinirvana Sutra, the Buddha says to the assembled monks,
“If one sees that there is much meat, one must not accept such a meal.
One must never take the meat itself. One who takes it infringes the
rule.” This is very clear, and as another example, in the Brahma’s Net
Sutra, he says, “ Disciples of the Buddha, should you willingly and
knowingly eat flesh, you defile yourself.” These teachings are repeated
strongly in many other sutras, including the Lankavatara Sutra and the
Surangama Sutra, both of which are foundational Mahayana Buddhist
scriptures. The cardinal precept in Buddhism is not to kill, and
animals are always explicitly included in this injunction.