You shall not hate your fellow countryman in your heart; you may surely reprove your neighbor, but shall not incur sin because of him. Leviticus 19:17

There is a special obligation upon friends to be helpful to one another in this matter. The laws of friendship require us to discover what things endanger us. . . .  Silence or concealment in this case is treachery. He is the most faithful friend, and worthy of most esteem and affection, that deal most plainly with us in reference to exposing our sin. He that is reserved in this case is but a false friend, a mere pretender to love, whereas, indeed, he hates his brother in his heart.

– David Clarkson

1622 – 1686