Sabbath the first of God's feast listed in Lev. 23:3 our Creator states, "Six days shall work be done, but the seventh day is the Sabbath of solemn rest, a holy convocation. You shall do no work on it; it is the Sabbath of the Lord in all your dwellings." We pray that we each are able to acknowledge that this is an appointed time of our Creator, God and that He alone can designate what is holy. In this case it is the seventh day that He, God has designated as holy. It is set apart from the other six days. In Gen. 2:3 God blessed and sanctified the seventh day.
There was never a question asked of Christ Jesus our Lord about which day was the Seventh day Sabbath. The question asked of Christ was about what work could be done on the Sabbath. Our Lord replied as recorded in Mark 2:27-28, that God had indeed made the Sabbath for mankind and that He was also Lord of the Sabbath. There was never any question as to whether it was to be observed or not. It is our prayer that our Creator, God, will grant you understanding of His Sabbath and the privilege to bare witness of HIM in your observance of it.