Vincent's NT Word Studies
3. Beholdest (blepeiv). Staring at from without, as one who does not see clearly.Considerest (katanoeiv). A stronger word, apprehendest from within, what is already there.
Mote (karfov). A.V. and Rev. The word mote, however, suggests dust; whereas the figure is that of a minute chip or splinter, of the same material with the beam. Wyc. renders festu, with the explanation, a little mote. In explaining the passage it is well to remember that the obstruction to sight is of the same material in both cases. The man with a great beam in his eye, who therefore can see nothing accurately, proposes to remove the little splinter from his brother's eye, a delicate operation, requiring clear sight. The figure of a splinter to represent something painful or annoying is a common oriental one. Tholuck ("Sermon on the Mount") quotes from the Arabic several passages in point, and one which is literally our Lord's saying: "How seest thou the splinter in thy brother's eye, and seest not the cross-beam in thine eye?"
Beam (dokon). A log, joist, rafter; indicating a great fault.
Robertson's NT Word Studies
7:3 {The mote} (to karfos). Not dust, but a piece of dried wood or chaff, splinter (Weymouth, Moffatt), speck (Goodspeed), a very small particle that may irritate. {The beam} (ten dokon). A log on which planks in the house rest (so papyri), joist, rafter, plank (Moffatt), pole sticking out grotesquely. Probably a current proverb quoted by Jesus like our people in glass houses throwing stones. Tholuck quotes an Arabic proverb: "How seest thou the splinter in thy brother's eye, and seest not the cross-beam in thine eye?"