Q: Which is the sixth commandment?
A: The sixth commandment is, Thou shalt not kill.

Q: What is required in the sixth commandment?
A: The sixth commandment requireth all lawful endeavours to preserve our own life, and the life of others.

Q: What is forbidden in the sixth commandment?
A: The sixth commandment forbiddeth the taking away of our own life, or the life of our neighbour unjustly, or whatsoever tendeth thereunto.

(Questions LXVII, LXVIII and LXIX from the Westminster Shorter Catechism.)