"I am going to propose a very plain and serious question to those who follow 'the Bible and the Bible only' to give their most earnest attention. It is this: Why do you not keep holy the Sabbath Day?
"The command of Almighty God stands clearly written in the Bible in these word: 'Remember the Sabbath day, to keep it holy. Six days shalt thou labor, and do all thy work; but the seventh day is the Sabbath of the Lord thy God; in it thou shalt not do any work.' Exodus 20:8-10.
"You will answer me, perhaps, that you do keep the Sabbath; for that you abstain from all worldly business and diligently go to church, and say your prayers, and read your Bible at home every Sunday of your lives.
"But Sunday is not the Sabbath day. Sunday is the first day of the week: the Sabbath day is the seventh day of the week. Almighty God did not give a commandment that men should keep holy one day in seven; but He named His own day, and said distinctly: 'Thou shalt keep holy the seventh day'; and He assigned a reason for choosing this day rather than any other -- a reason which belongs only to the seventh day of the week, and cannot be applied to the rest. He says, 'For in six days the Lord made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the Lord blessed the Sabbath day and hallowed it,' Exodus 20:11; Genesis 2:1-3. Almighty God ordered that all men should rest from their labor on the seventh day, because He too had rested on that day: He did not rest on Sunday, but on Saturday. On Sunday, which is the first day of the week, He began the work of creation; He did not finish it. It was on Saturday that He 'ended His work which he had made: and God blessed the seventh day, and sanctified it: because that in it He had rested from all His work which God created and made.' Genesis 1:2-3.
"Nothing can be more plain and easy to understand than all this; there is nobody who attempts to deny it. It is acknowledged by everybody that the day which Almighty God appointed to be kept holy was Saturday, not Sunday. Why do you then keep holy the Sunday and not Saturday?
"You will tell me that Saturday was the Jewish Sabbath, but that the Christian Sabbath has been changed to Sunday. Changed! But by whom? Who has authority to change an express commandment of Almighty God? When God has spoken and said, 'Thou shalt keep holy the seventh day,' who shall dare to say, 'Nay, thou mayest work and do all manner of worldly business on the seventh day: but thou shall keep holy the first day in its stead'? This is a most important question, which I know not how you answer.
"You are a Protestant, and you profess to go by the Bible and the Bible only; and yet, in so important a matter as the observance of one day in seven as the holy day, you go against the plain letter of the Bible, and put another day in the place of that day which the Bible has commanded. The command to keep holy the seventh day is one of the Ten Commandments; you believe that the other nine are still binding. Who gave you authority to tamper with the fourth? If you are consistent with your own principles, if you really follow the Bible, and the Bible only, you ought to be able to produce some portion of the New Testament in which this fourth commandment is expressly altered."
Excerpts from "Why Don't You Keep Holy the Sabbath Day?" pages 3-15, in The Clifton Tract, Volume 4, published by the Roman Catholic Church in 1869.