Our business is to raise ourselves to the highest status of life as preachers of Krsna’s message, and one should behave himself rigidly, then he should instruct others. Two things: Be himself exemplary, then teach others to be exemplary. If one has not come to that high standard, he cannot judge or criticize others. There is one saying from Bible: ‘Judge not, lest ye be judged.’ So how we can preach unless we are able to make judgements? That will not be possible. Only those who are above suspicion can judge others. One must himself act in such a way that he is always above suspicion. Then he can judge, then he can preach. But now you have no power to instruct. One who is not following himself, how he can instruct others?

Srila Prabhupada, Letter — 17 December, 1972