Honour thy father and mother; (which is the first commandment with promise;)
Note 4 at Eph 6:2: Children are to honor their parents even after they become adults, but the command to obey is temporary (Ga 4:1-2). Honor naturally leads to obedience if nothing is asked contrary to God's laws, but honor and obedience are not synonymous.
The Scriptures teach that when children marry, they are to leave their fathers and mothers and cleave unto their mates (Ge 2:24). Parental dominance that extends into marriage has been the source of many divorces and much marital strife. Yet, children are to honor their parents for all of their lives.
The word "honor" means "hold in respect; esteem" (American Heritage Dictionary). The Greek word "TIMAO," from which "honour" was translated, means "to prize, i.e. fix a valuation upon" (Strong's Concordance). There are many applications of children honoring their parents. Certainly, one of the violations of this today is children esteeming and respecting the opinions of their peers above those of their parents. The idea that parents are out of date, and therefore out of touch, is a devaluation of parents. Children should value the experience and wisdom of their parents more than their peers.
Note 5 at Eph 6:2: Paul quoted from Ex 20:12 and De 5:16 and said that this is the first commandment with promise. This is referring to the fact that this command about honoring parents was the first one of the Ten Commandments that gave a promise of blessing to those who obey it. The promised blessing is long life and things going well (Eph 6:3).