You are probably referring to what we read in Exodus 20:8 as part of the Ten Commandments.  That says, “Remember the sabbath day, to keep it holy.”  First, we must determine what the Sabbath day is.  The Sabbath day is Saturday, which is the seventh day of the week according to the Bible.  It was traditionally observed by the Jewish people from sunset on Friday to sunset on Saturday.  We read in Genesis 2:2-3, “And on the seventh day God ended his work which he had made; and he rested on the seventh day from all 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.” 

We further read in Exodus 20:10-11, “But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates: 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.”  While there is no scriptural evidence that the Sabbath was set aside as a special day before the giving of the Law to the Israelites in the Ten Commandments, we see this day was declared holy because it was the seventh day in which the Lord rested and so determined that His people should also rest on that day. 

To ‘remember’ the Sabbath day certainly implies it was already known and recognized as a day of rest.  To keep this day holy is to faithfully follow the instructions the Lord gave for this particular day.  We read in Leviticus 23:3, “Six days shall work be done: but the seventh day is the sabbath of rest, an holy convocation; ye shall do no work therein: it is the sabbath of the LORD in all your dwellings.”  There was no work to be done on this holy day. (Read Nehemiah 13:15-18.)  A person was to be executed for the slightest work, even gathering sticks on the Sabbath.  Numbers 15:32-35 tells us, “And while the children of Israel were in the wilderness, they found a man that gathered sticks upon the sabbath day. And they that found him gathering sticks brought him unto Moses and Aaron, and unto all the congregation. And they put him in ward, because it was not declared what should be done to him. And the LORD said unto Moses, The man shall be surely put to death: all the congregation shall stone him with stones without the camp.”

There was to be no activities for personal pleasure as we read in Isaiah 58:13-14, “If thou turn away thy foot from the sabbath, from doing thy pleasure on my holy day; and call the sabbath a delight, the holy of the LORD, honourable; and shalt honour him, not doing thine own ways, nor finding thine own pleasure, nor speaking thine own words: Then shalt thou delight thyself in the LORD; and I will cause thee to ride upon the high places of the earth, and feed thee with the heritage of Jacob thy father: for the mouth of the LORD hath spoken it.” 

To keep this day holy, there was to be no buying or selling as we read in Nehemiah 10:31, “And if the people of the land bring ware or any victuals on the sabbath day to sell, that we would not buy it of them on the sabbath, or on the holy day: and that we would leave the seventh year, and the exaction of every debt.”  These are just a few of the restrictions of activities that must be observed to keep the Sabbath day holy.

It must be noted that the keeping of the Sabbath day, as well as the entire Jewish Law was given to the Jews to observe and obey.  The words of the Law were expressly for the Jewish nation as we read in Exodus 19:5-6, “Now therefore, if ye will obey my voice indeed, and keep my covenant, then ye shall be a peculiar treasure unto me above all people: for all the earth is mine: And ye shall be unto me a kingdom of priests, and an holy nation. These are the words which thou shalt speak unto THE CHILDREN OF ISRAEL.” 

As the New Testament church, we observe the Lord’s Day (the first day of the week). (Matthew 28:1, John 20:19, Acts 20:7, 1 Corinthians 16:2).  We are NOT under the Law, but we are under grace. (Romans 6:14).  So, while the nation of Israel was commanded to keep the Sabbath Day holy, we are intreated to observe the Lord’s Day, which is the first day of the week and does not carry the limitations and consequences of the Sabbath Day under the Law.  (CC)  (700.4)