The sermon after my reading was not on murder; but something more interesting: the Sabbath.
The picture gives it away; the Sabbath is the pivot in the 10 Commandments between knowing God, and behaving in consistency with knowing God; behaving in a God-like, or God reflective manner, congruently with us being in Gods image (Genesis 1:26, where he defines our relationship with the rest of the creation, and it is not for worship, but for 'ruling') : that is, made to be God-like, and in relationship with God.
1. Don't worship other gods
2. Don't misrepresent God
3. Don't slander God
4. Remember the Sabbath
5. Honour your parents
6. No murder
7. No adultery
8. No stealing
9. No lies about others
10. No lust after others' things.
The first three are about God and our understanding of and relationship to him.
The fourth is part of our being like God. When God finished creating, he 'rested'. As Genesis 2 shows us, as the account zooms into man's creation detail, the resting is for relationship: God walks in the Garden seeking his creatures. Genesis 3:8. Alas, broken!
Thus our Sabbath is for relationship: for relationship with the ones God wants us to relate to (him: 1-3) and those around us (commandments 5-6, telling us what it is to relate in reflection of God).
God 'rested' to enjoy his creation; we are to 'rest' to enjoy God...and his creation; that is each other.