The Imitation of Christ, by Thomas a Kempis, tr. by William Benham , at sacred-texts.com
We must not trust every word of others or feeling within ourselves, but cautiously and patiently try the matter, whether it be of God. Unhappily we are so weak that we find it easier to believe and speak evil of others, rather than good. But they that are perfect, do not give ready heed to every news-bearer, for they know man's weakness that it is prone to evil and unstable in words.
2. This is great wisdom, not to be hasty in action, or stubborn in our own opinions. A part of this wisdom also is not to believe every word we hear, nor to tell others all that we hear, even though we believe it. Take counsel with a man who is wise and of a good conscience; and seek to be instructed by one better than thyself, rather than to follow thine own inventions. A good life maketh a man wise toward God, and giveth him experience in many things. The more humble a man is in himself, and the more obedient towards God, the wiser will he be in all things, and the more shall his soul be at peace.