These verses are most significant on this subject. After the unity of God, human beings should, through their attitude of love, affection, and kindness, give priority over all other things to their parents who have reached an old and difficult age.
Further, the verses speak of the situations when the behaviour of one or both of the parents becomes extremely trying and sometimes offensive. In response to that, not even a mild expression of disgust or disapproval should pass one's lips. On the contrary they should be treated with profound respect.