Qualification of the precept, “Be swift to hear”: “Be ye doers ... not hearers only”; not merely “Do the word,” but “Be doers” systematically and continually, as if this was your regular business. James here again refers to the Sermon on the Mount (Mat 7:21-29).
deceiving your own selves - by the logical fallacy (the Greek implies this) that the mere hearing is all that is needed.