First, we should note there is but one sabbath each week. It falls on the seventh day (Exodus 16:26). No one can change that fact. Despite what many say, Sunday is not the sabbath.
Second, the sabbath was bound by God upon the children of Israel at Sinai (Nehemiah 9:13,14). It had not previously been known or kept by their fathers (Deuteronomy 5:2,3). The children of Israel were to keep the sabbath as a continual sign of their covenant with God (Exodus 31:12-17).
Third, the law of the sabbath was a part of the law of Moses. It was delivered only to those who lived under that law (Romans 3:19). Jesus died to take the law of Moses out of the way because it was against man (Colossians 2:14). Like the wife whose husband has died, we are no longer bound to the law (Romans 7:1-4).
Fourth, the blessings we enjoy do not come from the law, but the Seed of Abraham, who is Jesus Christ (Galatians 3:8-14). Just as Jeremiah had foretold, God made a new covenant. Instead of writing in stone, He wrote it on hearts (Jeremiah 31:31-33).
Fifth, the first day of the week was important to Christians in the first century. Jesus was raised from the dead on the first day (Mark 16:1-8). About three thousand souls were added to the church on Pentecost, which was always on the first day (Acts 2; Leviticus 23:15,16). The church in Troas, along with Paul and his companions, assembled to partake of the Lord's supper on the first day (Acts 20:6,7). The Corinthian brethren were to "lay by in store" on the first day of the week (1 Corinthians 16:1,2).
Christians understand the sabbath was to be faithfully kept by those living under Moses' law. However, we are not bound to keep it today. Under Christ's reign, we remember the death, burial, and resurrection of Christ on the first day of the week.