Some have suggested that the introduction of the law (“I am the LORD your God, who brought you out of the land of Egypt, out of the house of bondage”), as well as the restatement of the fourth commandment in Deuteronomy (which discusses the Jews’ deliverance from Egypt instead of God’s creation of the world), is evidence that the Sabbath was an ordinance for the Jewish nation and not New Testament believers. Such an argument falls to the ground when one considers that the preface concerns all the commandments, not just the fourth. No one would hold that lying, adultery, theft and murder were permissible outside the Jewish nation. Furthermore, the salvation of Israel from Egypt typified the salvation of believers from their slavery to sin and the world. “In Exodus, reference is made to the creative work of God undertaken in six days, after which God rested on the seventh day. The two reasons [Ex. 20:11; Dt. 5:15] complement each other and both emphasize man’s dependance on God. To rest on the sabbath day was to remember that man, as a part of God’s created order, was totally dependent on the Creator; man’s divinely appointed task to have dominion over the created order (Gen. 1:26) carried with it also the privilege of sharing in God’s rest. The Exodus, too, was a type of creation and thus forms an analogy to the creation account in Genesis. The Exodus from Egypt marks in effect the creation of God’s people as a nation, and the memory of that event was also a reminder to the Israelites of their total dependence upon God.” 
…The prophets treated the Sabbath as a moral ordinance that was also binding on the Gentiles. In Isaiah 56 Jehovah speaks not just to the Jews, but also to the Gentiles, concerning the duties which all men owe to one another and to God: “Keep justice, and do righteousness, for my salvation is about to come, and my righteousness to be revealed. Blessed is the man who does this, and the son of man who lays hold on it; who keeps from defiling the Sabbath, and keeps his hand from doing any evil” (vv. 1-2). Note that keeping the Sabbath is as much a duty to the Gentiles as keeping justice and not doing evil.
Extract from Schwertley, Brian, The Christian Sabbath: Examined, Proved & Applied
The sabbath is a part of loving the Lord with all your heart, soul, mind and strength. This article is well worth reading to gain understanding about a commandment that may seem at first a little bit odd, compared to the obvious wickedness of false witness, murder and adultery, etc. Its good to know more about the sabbath both for our personal walk and also for our evangelism.