Children, obey your parents in the Lord: for this is right. The first duty of children is obedience, and "in the Lord," i.e. in Christ, this duty is confirmed. The ἐν κυρίῳ qualifies, not "parents," but "obey," and indicates that the element or life which even children lead in fellowship with Christ makes such obedience more easy and more graceful.
The duty itself rests on the first principles of morality—"for this is right." It is an obligation that rests on the very nature of things, and cannot change with the spirit of the age; it is in no degree modified by what is called the spirit of independence in children.