An ill attitude of jealousy in the heart towards another magnifies some little thing while ignoring one's own malice.
"Self-judgment by grace always tends to promote humility and love..." (Bible Treasury 6:375).
W. Kelly said: "Judge not that ye be not judged"... refers not to that which is plain, but to what is concealed; to that which, if it does exist, God has not yet laid the evidence before the eyes of His people... We are bound to watch against the spirit of SURMISING evil or IMPUTING MOTIVES (Lectures on Matthew, in loco.).
The mote, of course, was but little, but it was made a great deal of, and the beam, an enormous thing, was passed by. The Lord is bringing out... the danger of a SUSPICIOUS JUDICIAL SPIRIT. And He shows that the way to deal rightly, if we desire the good of His people and their deliverance from evil, IS TO BEGIN WITH SELF-JUDGMENT... Let us begin with the grave faults...in ourselves:...if I begin with this, I shall then see clearly what concerns others;... (W. Kelly, Lectures on Matthew, in loco.) It is clear that unjudged self breeds a SUSPICIOUS JUDICIAL SPIRIT which presumes to judge undisclosed motives. It is this which the Lord condemns in Matt. 7 (and not the commendable judging of evil which we are commanded to do —e.g., 1 Cor. 5:12, 1312For what have I to do to judge them also that are without? do not ye judge them that are within? 13But them that are without God judgeth. Therefore put away from among yourselves that wicked person. (1 Corinthians 5:12‑13)).
The discovery of a mote in a brother's eye..."Beholdest" means that it is a continuous thing. It further shows our overlooking all the other praise-worthy features in the brother in order to focus on the smallest spot—the least speck that is wrong in him, though it can hardly be discerned... If I cultivated the habit of self-judgment, instead of being severe with the sin of others and indulgent with my own, I should then "consider the beam" in my own eye, that is, I should first deal with my own faults with unsparing judgment, and then with my brother's if necessary in the spirit of meekness... Those who are most faulty are too often the least conscious of it, and usually the first to find the faults of others, and the most unsparing to condemn them. It was not the brother with the mote in his eye that discovered the beam in his brother's, but he with the beam, although, undoubtedly, the former could see more clearly of the two. May we have grace to mortify our own members, for if we would judge ourselves, we would not be judged... The motive must be nothing less than love... first cast out the beam out of thine own eye (from Matters of First Importance, by E. V.).
"The faultfinder commences not with himself."
"Pray for them which despitefully use you."