The Literal Commandment
Whatever I command you, you shall be careful to do; you shall not add to nor take away from it. (Deuteronomy 12:32)
This not only says we should not change the number of commandments (neither add nor take away) but it also says we should not add or take away from each commandment. For example, it is not enough to just remember the Sabbath day... we must also keep it holy (Exodus 20:8). To do only one or the other would "take away" from the commandment.