For further explanation, I do not think it wrong to admonish the sinner. After all, that is a spiritual work of mercy. However, I think we can draw from both the Dialogue and the Gospel that the only state in which it is meritorious for us to admonish the sinner is when we deal with our own sins FIRST. Finally, this quote can be found in the section of the Dialogue titled: "Truth" - or page 190 of the Classics of Western Spirituality edition.