Rebuke with soft words and hard arguments. – Proverb

Every reform, however necessary, will by weak minds be carried to an excess, which will itself need reforming. – Samuel Taylor Coleridge

Some who will not speak against another, in the end does them harm. – Proverb

People who love soft methods and hate iniquity forget this, — that reform consists in taking a bone from a dog. Philosophy will not do it. – John Jay Chapman