Remembering the Sabbath and keeping it holy is one of the Ten Commandments and part of the Old Covenant. However, Jesus’ death and resurrection established a new and far superior Covenant through His blood, making the Old Covenant and its requirements obsolete.
Hebrews 8:7 says, “For if there had been nothing wrong with that first covenant, no place would have been sought for another.” Hebrews 8:13 also states, “By calling this covenant new, he has made the first one obsolete; and what is obsolete and outdated will soon disappear.”
Believers in Jesus Christ are not required to obey the Sabbath and its requirements but should follow the law of Christ, which is summarized in Matthew 22:37-39, “‘You shall love the Lord your God with all your heart, with all your soul, and with all your mind.’ This is the first and great commandment. And the second is like it: ‘You shall love your neighbor as yourself.’” Adherence to this and other commands in the New Testament is not required for salvation but should be done freely and willingly in response to God’s great love and sacrifice on the cross.
Interestingly, nine of the Ten Commandments in the Old Testament fall within the law of Christ. The only Commandment excluded is Sabbath observance. This exclusion is because Jesus Himself is the Sabbath rest for all believers under the New Covenant.
When Jesus sat down at the Father’s right hand, He rested from His work of redemption. Since nothing more needed to be done or added, Jesus provides a permanent Sabbath rest to all who come to Him in faith for what He accomplished on their behalf. Therefore, obeying the Sabbath and its requirements is no longer necessary.
Hebrews 12:2 says, "Fixing our eyes on Jesus, the author and perfecter of faith, who for the joy set before Him endured the cross, despising the shame, and has sat down at the right hand of the throne of God."
Colossians 2:16-17 states, “Therefore no one is to act as your judge in regard to food or drink or in respect to a festival or a new moon or a Sabbath day— things which are a mere shadow of what is to come; but the substance belongs to Christ.”
Hebrews 4:1-3 says, “Therefore, let us fear if, while a promise remains of entering His rest, any one of you may seem to have come short of it. For indeed we have had good news preached to us, just as they also; but the word they heard did not profit them, because it was not united by faith in those who heard. For we who have believed enter that rest.”
Hebrews 4:9-11 declares, “So there remains a Sabbath rest for the people of God. For the one who has entered His rest has himself also rested from his works, as God did from His. Therefore let us be diligent to enter that rest, so that no one will fall, through following the same example of disobedience.”
I hope this information helps you understand why believers under the New Covenant are not required to keep the Sabbath or obey its requirements.