Cattāri Brahmavihārā

28. One who wants to admonish another should first investigate: “Am I or am I not one who practices utter purity in body and speech? Am I or am I not possessed of utter purity in body and speech, flawless and untainted? Are these qualities manifest in me or not?” If they are not, there are undoubtedly people who will say: “Come now, practice correct bodily and verbal conduct yourself.” There are people who would say this.
Again, one who wants to admonish another should first investigate: “Have I developed a mind of goodwill, free from malice towards my fellows in the holy life? Is this quality established in me or not?” If he has not, there are undoubtedly people who will say: “Come now, develop a mind of goodwill yourself.” There are people who would say this.

Anguttara Nikaya V.79