Q: What is required in the fourth commandment?
A: The fourth commandment requires the keeping holy to God such set times as he has appointed in his word; expressly one whole day in seven, to be a holy sabbath to himself
Exodus 31:13 You are to speak to the people of Israel and say, ‘Above all you shall keep my Sabbaths, for this is a sign between me and you throughout your generations, that you may know that I, the Lord, sanctify you.'
The idea of sabbath, that is, "holy rest", is so essential to the life of a Christian. The sabbath shows and reminds us of a great reality. It is God's invitation to his people to participate in his own holy rest. The seventh day of Creation was set aside, ordained by God, to be a day of holy rest. This makes the sabbath not merely a command of the law, but rather, it makes the sabbath a "Creation Ordinance", ordained by God in his work of creation. For the Old Testament people of God, the sabbath was a reminder of their need for rest, and a reminder that true rest and peace comes from communion with God. Likewise, and more fully understood, the New Testament community finds our holy rest in our union with Jesus Christ. It is in Christ that we find rest from the burden of the law and a rest from the burden of our sins. Because of this, we remember the sabbath and keep it holy, not out of obligation, not only because God commands it, but also out of delight because, as Exodus 31 says, doing so assures us that the LORD God is indeed sanctifying us. The sabbath speaks the reality of the gospel into our lives, and the command to remember it and keep it holy is one of God's ordained means of grace for the good of his people and for his own glory.