Institutes of the Christian Religion (1559) - John Calvin
Book 2 - God the Redeemer
Chapter 8 - Explanation of the Moral Law:
The 10 Commandments
Sections 39-40 - Sixth Commandment - Don't Murder
Section 39 - The commandment
Watch out for the physical safety of others.
Murder of the mind: harbor no anger to others.
1 John 3:15; Matt 5:22.
Section 40 - The reason for this commandment
Man is made in God's image.
He is our fellow; we share the same flesh, and so ought not destroy his.
This extends beyond physical murder, to attempting physical harm,
and to refraining from helping when you can.