Howbeit in vain do they worship me, teaching for doctrines the commandments of men. Mark 7:7.
Jesus' custom was to keep the Sabbath (Luke 4:16). It had been His custom when He lived in Nazareth, working in the carpenter shop. It was a custom that He continued all through His life. He was the Creator, and yet we see Him resting on the Sabbath day as He Himself had commanded. Obviously, He was giving us an example that we can follow today.
Jesus warned the people against their traditions. He had no time for anything based simply on tradition when it came in collision with His Father's commandments. It's interesting to make a list of the traditions that we have today. Some of us think that it is a sin to open our eyes during prayer! That's just a tradition. There's no basis in Scripture for that. Some people feel it's a sin to put anything on top of the Bible. That's a tradition. Some parents tell their children it's a sin to take part in the communion service before they have been baptized. Another tradition. Should we throw out all traditions? No, you don't throw them out arbitrarily. Some of the traditions may have good reasons for them. But whenever tradition comes in collision with the truth of God, then the tradition goes. Jesus spoke to this point, "Howbeit in vain do they worship me, teaching for doctrines the commandments of men. For laying aside the commandments of God, ye hold the tradition of men....Full well ye reject the commandments of God."
Any kind of false Sabbath or false day of worship that the world has gotten into the habit of observing is strictly a tradition, because you don't find it in Scripture at all. If you want to keep the Sabbath of the Bible, you are going to keep the seventh day, according to Scripture.
The most oft-given reason for keeping Sunday is that it is the day of Jesus' resurrection. It's a nice-sounding reason--but it has no Bible base. If you are going to follow the Bible teachings, you will keep the seventh day. For those who want to honor the resurrection, we have the service of baptism. That's the Scripture memorial for the resurrection. Jesus rested at the end of Creation, and rested again in the grave after He had finished His work on the earth. And today He invites us to rest in memorial of the works of creation and redemption He has accomplished for us.