It is a common misconception that the Sabbath is "Jewish" and "Old Covenant," probably because most Christians, worshipping on Sunday, believe that Jesus changed the Sabbath from Saturday to Sunday for His followers. Nothing could be further from the truth!
There are three primary biblical reasons why the seventh-day Sabbath is not Jewish. We find the first in Exodus 19-20. Notice Exodus 19:6:
"And you shall be to Me a kingdom of priests and a holy nation." These are the words which you shall speak to the children of Israel.
Though it may seem a fine point, the Jews are not all of Israel but only one tribe among twelve (see Exodus 1:1-7). All Israel was to keep the Sabbath, but most of the tribes apostatized, so that by Jesus' day, only Judah, Benjamin, and Levi kept it. One could say, therefore, that the Sabbath is "Israelite," but this would still be partially wrong.
The apostle Paul takes great pains to show that Israel, for the time being, has been set aside as the "nation" with whom He is primarily working (Romans 9-11). He begins his theological argument by saying that the church of God is now the new Israel (Romans 9:6-8). All those who follow the faith of Abraham are Abraham's spiritual descendants (Romans 4:13-17; see Galatians 3:29; 4:22-31). In Galatians 6:16, Paul specifically calls the church "the Israel of God." Therefore, the commandments of God—including the Sabbath—given to Israel are in force in the church. The Sabbath is a Christian doctrine and practice.
The second biblical reason the Sabbath is not "Jewish" is found in the words of Christ Himself. Notice Mark 2:27-28:
And He said to [the Pharisees], "The Sabbath was made for man, and not man for the Sabbath. Therefore the Son of Man is also Lord of the Sabbath."
This passage is unassailable! God created the Sabbath for all mankind, not just for the Jews, not just for the church! As its Creator and the Firstborn of mankind, Jesus, the Son of Man, is also the master or governor of the Sabbath, so He should know for whom it is intended: humanity. A search of the New Testament from Matthew to Revelation will turn up no command or even an allusion to the effect that Christ nullified or changed the seventh-day Sabbath.
The third reason is that the Sabbath existed before any of the Jews did! Genesis 2:2-3 reads:
And on the seventh day God ended His work which He had done, and He rested on the seventh day from all His work which He had done. Then God blessed the seventh day and sanctified it, because in it He rested from all His work which God had created and made.
The seventh day has been holy, blessed, and sanctified for as long as mankind has been in existence—minus one day. The first Jew did not appear until millenia later. Similarly, God says that Abraham "obeyed My voice and kept My charge, My commandments, My statutes, and My laws" (Genesis 26:5), showing that God's law predated the Old Covenant. The annual holy days were part of God's statutes, and the Sabbath is obviously the fourth of His Ten Commandments.
Far from being a "Jewish" day, the Sabbath is a gift of God for everyone.