Then I contended with the nobles of Judah, and said to them, “What evil thing is this that you do, by which you profane the Sabbath day? Did not your fathers do thus, and did not our God bring all this disaster on us and on this city? Yet you bring added wrath on Israel by profaning the Sabbath.” Nehemiah 13:17-18

Technically the Sabbath is sundown Friday until sundown on Saturday. Very few Christians truly worship on the Sabbath but choose Sunday as a day of worship since Christ rose from the grave on the first day of the week (Sunday). Sunday is viewed as “the Lord’s Day” as in Rev 1:10 – I was in the Spirit on the Lord’s Day.

I believe one should take time to worship God in a fellowship setting of other believers. Israel had a called assembly just as the church is a called assembly.
I am thankful for those working on the Sabbath or Sunday.
Doctors, nurses, firefighters, police, and the military continue to operate in preserving lives because of work schedules.
Hopefully, they don’t work every Sabbath or Sunday so they too can worship in an assembly.
The contention in Nehemiah’s day was in dealing with people that did not worship at all but treated the Sabbath no different than any other day of the week. It was business as usual.
Many people today do the same thing. The Sabbath or Sunday is just another day to them to open their business, go fishing, go to the beach, mowing the grass, or some other secular activity, which they do on a consistent basis every time.

Could this thought on the part of Christians lead to Revelation 3:14-17?
If they were saying, “I am rich, have become wealthy, and have need of nothing” then they had no need of the Sabbath, Sunday, or church.

Take a look around!
We are there!