Honor your father and your mother, as the Lord your God has commanded you, so that your days may be prolonged and so that it may go well with you in the land which the Lord your God gives you.
When we were kids, we listened to Mom and Dad for several reasons. If we wanted to be on their good side and perhaps try to get something out of them, we were polite. If we wanted to avoid punishment for misbehaving, we were well-behaved. Pretty much if we wanted to make sure that life was going to go well for us, we were kind to them. We might see these as rather selfish motives, but it seems that we were on to something. Yes, parents should be obeyed and honored because they are worthy of it. They have been placed in authority over their children, and honor and obedience should be theirs, but even God has promised that this good behavior will be rewarded.
I have heard it taught, and it is not untrue, that this is the only commandment which comes with a promise. The other nine tell us of behavior which conforms to the character of God, but they stop there. This one, however, tells us that we gain something specific by following this commandment. The scriptures does not indicate why this is the case, but the historical context here might give us a hint. God had just delivered Israel from Egypt, and we know that part of their problem was obedience to their Father in heaven. Maybe God was trying to instill in them the importance of obeying their heavenly Father by teaching the value in obeying earthly parents. One is a shadow of the other, and this would be a lesson inherently passed down through the generations if practiced correctly.
One thing we can say for sure is that this commandment is distinctly important to God because of the promise He has attached to it. We can be like children and obey it for the sake of gaining the promise, or we can look at the promise as our indicator that this commandment is that important to God. It should stick out to us as something worth noting. God holds this good behavior so highly that He makes life more fruitful for those who practice it. Let us seek the good fruit available to us, but let us practice this commandment out of honor. Father, make us more obedient and honorable to our parental figures that our days would be longer and our lives more fruitful.