How do we know the Sabbath is not obligatory for Christians?

The New Testament makes it abundantly clear that Christians are not bound by the works of the law, including the Sabbath. Galatians 5:3 shows that those who attempt to keep the law must keep it all and are thus under a curse. Moreover, Paul teaches in Ephesians 2:15 that Christ has made void the enmity of the law's commandments, indicating a significant transition from legalism to grace. The author of Hebrews further expounds on this by likening the Sabbath of the old covenant to a shadow of the true rest that believers find in Christ. This understanding emphasizes that our justification comes through faith in Christ, not through adherence to the law, highlighting that the ceremonial aspects of the old covenant, including the Sabbath, are now fulfilled in Him.