Christ was asked in the Bible, "Lord, what must I do to enter the kingdom of Heaven?" Christ replied, "keep the commandments" and named a few of them. Since keeping the Sabbath was one of them, shouldn't we keep the Sabbath today?
You are referring to the question asked by the rich young ruler, found in Matthew 19:16-22: "Now behold, one came and said to Him, "Good Teacher, what good thing shall I do that I may have eternal life?" So He said to him, "Why do you call Me good? No one is good but One, that is, God. But if you want to enter into life, keep the commandments." He said to Him, "Which ones?" Jesus said, "'You shall not murder,' 'You shall not commit adultery,' 'You shall not steal,' 'You shall not bear false witness,' 'Honor your father and your mother,' and, 'You shall love your neighbor as yourself.'" The young man said to Him, "All these things I have kept from my youth. What do I still lack?" Jesus said to him, "If you want to be perfect, go, sell what you have and give to the poor, and you will have treasure in heaven; and come, follow Me." But when the young man heard that saying, he went away sorrowful, for he had great possessions."
Jesus told the young man that he needed to keep the commandments and listed six of the Ten Commandments as examples. Though the commandment for keeping the Sabbath was not listed, it is understood that Jesus was telling the young man to keep all of God's commands. The young man responded that he had been keeping the commands, but wanted to know what more he should do. Jesus gave him two more things to do: sell all that he had and give it to the poor and follow Jesus. Though the earlier list were things found in the Old Testament, the second set of things Jesus asked of the young man is not found in the Old Testament. Jesus proves that the young man was unwilling to fully commit his life to God.
When using this passage as proof that Christians should keep the Ten Commandments, a fundamental point is overlooked: the law changed when Jesus died on the cross. "And you, being dead in your trespasses and the uncircumcision of your flesh, He has made alive together with Him, having forgiven you all trespasses, having wiped out the handwriting of requirements that was against us, which was contrary to us. And He has taken it out of the way, having nailed it to the cross" (Colossians 2:13-14). Paul argues that the law had to change in order for salvation to be brought to the uncircumcised (the Gentiles). Because a person did not have to be a Jew to be a Christian, Paul further argued that Christians are not to be judged by their keeping former requirements, such as food and drink regulations, festivals, and the Sabbath. "So let no one judge you in food or in drink, or regarding a festival or a new moon or sabbaths, which are a shadow of things to come, but the substance is of Christ" (Colossians 2:16-17).
At the time that Jesus spoke to the rich young man, the Law of Moses was still in effect. If the young man desired eternal life, he needed to obey God's commands. Interestingly, the ones Jesus selected as examples were among those which remained the same between the Old and New Law. Just because the law would be changing in a short while, it wasn't an excuse to rebel against the currently existing laws.
Therefore, this verse does not prove that the keeping of the Sabbath was a law carried over into Christ's Law. The law under discussion was the Mosaical Law which was in effect at that time.