Malachi 3:6 For I am the LORD, I change not;
Jesus says, I am the same, yesterday and today.
The sabbath was given to mankind before the fall of men. God instituted two things at creation week. The marriage between husband and wife and the Sabbath day.
Jesus says I am Lord of the Sabbath.
The seventh day was part of creation week. If we see the sun, moon, stars, trees, animals, fish, plants and trees are all part of creation and like all those things you see the seventh day is still with us today.
What is the relevance of the Sabbath day and the new heaven and earth? I am not aware if people know, that the Sabbath will be kept in heaven aswell.
You will need to ask yourself which law was nailed to the cross? Was it the ceremonial law or the ten commandments?
The sanctuary service (tabernacle service) or the Hebrew feasts was the end goal to deal with sin in the Old testament until Jesus came to fulfill all the requirements of the law and was obedient unto death. When Jesus died the earthly sanctuary was torn in two. But as Hebrew states we have a heavenly Priest which makes intercession for us. The Israelites do not have to sacrifice animals any longer because Christ the lamb was sacrificed already which means the sacrificial service had ceased at the cross. All the Hebrew feasts was pointing to the life and death of our Lord and saviour Jesus Christ.
The ten commandments is still binding, it would not save us. Yet it points out sin. What is sin? It is the transgression of the law. It is lawlessness. God wrote the ten commandments on solid stone signifying the temperament nature of the law. He also wrote it with His own finger. Jesus warned that He never came to abolish the law but to fullfill it. He said not one jot or title would be remove until everything has been done and heaven and earth has past away.
Why do believers tend forget the one commandment, Jesus is saying to 'Remember the Sabbath to keep it holy'. Why keep only the nine commandments?
In the end, you need to prayerfully study this subject to satisfy yourself and ask God for wisdom and understanding.
Blessings