Judge not, lest ye be judged

Brigham Young’s words:

Judge not, that ye be not judged. Let no man judge his fellow being, unless he knows he has the mind of Christ within him. We ought to reflect seriously upon this point; how often it is said "Such a person has done wrong, and he cannot be a Saint, or he would not do so." How do you know? We hear some swear and lie; they trample upon the rights of their neighbor, break the Sabbath by staying away from meeting, riding about the city, hunting horses and cattle, or working in the canyons.

Brigham Young also warns:

• Do not judge such persons, for you do not know the design of the Lord concerning them; therefore, do not say they are not Saints. What shall we do with them? Bear with them … Judge no man. A person who would say another is not a Latter day Saint, for some trifling affair in human life proves that he does not possess the Spirit of God.
  

Thanks to Wally Goddard for pointing these quotes out.