No, I do not believe that one must keep the Sabbath for many reasons.
First, in studying the covenants, I believe that the Sabbath was the sign or seal of the Mosaic Covenant.
There is no mention of the keeping of the Sabbath from Adam to <oses. Though the Ten Commandments are spoken of as the Moral Law, the fourth commandment was actually a ceremonial law. It was this ceremony that was attached to the Mosaic Covenant as its seal.
In the New Testament, Jesus clarified that the Sabbath was made for man and not man for the Sabbath. Jesus moved on to present Himself as the Lord of the Sabbath. He is higher than the keeping of the day. Even in OT times when Israel kept the Sabbaths, God condemned them for their hypocritcal observances (Is. 1:10-17); and predicted the cessation of their feast days and Sabbaths (Hos. 2:11) Paul taught in Col. 2:11, 16-17 that the holy days, new moon and Sabbath days were merely a shadow of things to come and had been abolished at the Cross.
Further, all of the moral commandments of the Mosaic Covenant are repreated and endorsed in the NT, with only one exception, the Sabbath. This ceremony was never stated as a requirement for New Testament believers.
Paul clearly tells us that the Old Covenant was old, decaying and ready to vanish away. It was a ministration of death and was to be done away with (2 Cor. 3:1-18; Heb. 8:6-13). The New Covenant has its own sign and seal, even the true and spiritual rest, which is the baptism of the Holy Spirit. Finally, Hebrews clearly states that in Christ, the believer finds true Sabbath rest. He ceases from his own work and rests in the finished work of Christ. It is not in the keeping of a day, but in receiving of a person, Jesus Christ our Lord, that one finds the rest.
Further, I would like to finish with this. The Ten Commands were a "schoolmaster" to point to Christ. The entire Mosaic Law, which is the only Covenant based on works, was given by God to His people to point to their (our) need for Christ. Galations 3 says that Christ hath redeemed us from the curse of the law. Galations 3:23, 25 says "but before faith came, we were kept under the law...but after that faith is come, we are no longer under a school master."
Basically, bottom line is, we keep the ten commandments, excluding the ceremonial sabbath, because we believe in the Royal Law "Love the Lord thy God with all thy heart mind and soul, and love thy neighbor as thyself." Not because it is the Mosaic Law.
Just my views based on research. If they don't belong to you that is fine, but I encourage you to study scripture for yourself.
Blessing,
Cynthia