Law 4- Observe the Sabbath day by keeping it holy

1. I am the LORD your God, you shall have no other gods before me.
2. You shall not make for yourself an idol
3. You shall not misuse the name of the LORD your God
4. Observe the Sabbath day by keeping it holy

5. Honor your father and your mother
6. You shall not murder.
7. You shall not commit adultery.
8. You shall not steal.
9. You shall not give false testimony against your neighbor.
10. You shall not covet.

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it is said the first 4 commandments deal with God to man relationship and last six deal with man-to-man (though all are of course in relationship to God).

I do not know if they are arranged in order of importance. But if it is so, then Observe the Sabbath day by keeping it holy seems quite important, even placed before the last man-to-man Laws.