On how to reason when tempted to find fault with another
When then we are brought under the necessity of finding fault with any, let us first consider whether the sin be such as we have never had; secondly that we are yet men, and may fall into it; then, whether it be one that we have had, and are now without, and then let our common frailty come into our mind, that pity and not hate may go before correction. Should we find ourselves in the same fault, let us not reprove, but groan with the offender, and invite him to struggle with us. Seldom indeed and in cases of great necessity is reproof to be employed; and then only that the Lord may be served and not ourselves.
On the common faults of those who judge
The Lord having admonished us concerning hasty and unjust judgments; and because that they are most given to rash judgment, who judge concerning things uncertain; and they most readily find fault, who love rather to speak evil and condemn than to cure and correct; a fault that spring either from pride or jealousy - therefore He subjoins, "Why seest though the mote in thy brother's eye, and seest not the beam in thy own eye?"
On judgement with uncertainty
1) I suppose the command here to be no other than that we should always put the best interpretation on such actions as seem doubtful with what mind they were done. But concerning such as cannot be done with good purpose, as adulteries, blasphemies, and the like, He permits us to judge; but of indifferent actions which admit of being done with either good or bad purpose, it is rash to judge, but especially to condemn.
2) There are two cases in which we should be particularly on our guard against hasty judgments, when it does not appear with what mind the action was done; and when it does not yet appear, what sort of man any one may turn out, who now seems either good or bad. Wherefore he should neither blame those things of which we know with what mind they are done, nor so blame those things which are manifest, as though we despaired of recovery.