The Sabbath is God's commandment to be kept until the end of the world.

[Matthew 24:20-21]
Pray that your flight will not be in winter or on the Sabbath.
For there will be great tribulation at that time, such as has not been from the creation of the world until now, and never will be.

What if we don't keep the Sabbath?

[Matthew 7:21-23]
"Not everyone who says to me, 'Lord, Lord,' will enter the kingdom of heaven, but only he who does the will of my Father who is in heaven.
Many will say to me on that day, 'Lord, Lord, did we not prophesy in your name, and in your name drive out demons and perform many miracles?'
Then I will tell them plainly, 'I never knew you. Away from me, you evildoers!'

God clearly said that those who practice lawlessness will never go to heaven.

So, is the Sabbath worship God's will? Or is it God's will to keep Sunday worship that is not in the Bible?

It is God's will to keep the Sabbath

If you are a believer in God, of course, you must keep God's commandments.

It is the Church of God that keeps the Sabbath according to the will of God according to the Bible.

I hope that you keep the Sabbath and receive all the blessings that God has promised.