Exodus 20:10

But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates:

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How many people work on the seventh day? I believe that you'll find this law from God was changed by man. The following is just one of many references...

Council of Laodicea

"Christians should not Judaize and should not be idle on the Sabbath, but should work on that day; they should, however, particularly reverence the Lord’s day and, if possible, not work on it, because they were Christians" (Canon 29 [A.D. 360]).

God is very specific concerning the Sabbath as mentioned below in one of many warnings...

Exodus 31:15 Six days may work be done; but in the seventh is the sabbath of rest, holy to the LORD: whosoever doeth any work in the sabbath day, he shall surely be put to death.

Choose wisely which day God wants you to observe as His Sabbath.