"There is the case, headman, where a Tathagata appears in the world, worthy and rightly self-awakened, consummate in clear knowing & conduct, well-gone, a knower of the cosmos, unexcelled trainer of those to be tamed, teacher of human & divine beings, awakened, blessed. He, in various ways, criticizes & censures the taking of life, and says, 'Abstain from taking life.' He criticizes & censures stealing, and says, 'Abstain from stealing.' He criticizes & censures indulging in illicit sex, and says, 'Abstain from indulging in illicit sex.' He criticizes & censures the telling of lies, and says, 'Abstain from the telling of lies.'
"A disciple has faith in that teacher and reflects: 'The Blessed One in a variety of ways criticizes & censures the taking of life, and says, "Abstain from taking life." There are living beings that I have killed, to a greater or lesser extent. That was not right. That was not good. But if I become remorseful for that reason, that evil deed of mine will not be undone.' So, reflecting thus, he abandons right then the taking of life, and in the future refrains from taking life. This is how there comes to be the abandoning of that evil deed. This is how there comes to be the transcending of that evil deed.
https://www.accesstoinsight.org/tipitak ... .than.html