Anyone who breaks one of the least of these commandments and teaches others to do the same will be called least in the kingdom of heaven, but whoever practices and teaches these commands will be called great in the kingdom of heaven.
If I haven't mentioned it before, the phrase, "the kingdom of heaven," or "the kingdom of God," is referring to what it would be like to have God as king. This is the easiest way to understand this title.
So, here we have it, if you go against the commands of the king, and teach others to do the same, then you are the least citizen of the kingdom, and will be called so. A pretty serious warning. When I read this, what came to my mind are those people who feel like it is OK to do about anything. Sometimes I wonder if they have gone too far. They claim to be anti-legalistic, but what they end up doing is getting rid of every rule that has ever been imposed upon them. But in this verse, we aren't to live without commands. We, as citizens of this heavenly kingdom are to keep the commands.
And in keeping the commands of God, we are to teach others to do the same. We will be called great in the kingdom, if we are obedient to the king.