Resolved, never to speak evil of anyone, so that it shall tend to his dishonor, more or less, upon no account except for some real good. Jonathan Edwards (theologian)
I love the flesh. I'm a pagan. "Who are they who speak evil of the clay? The very stars are made of clay like mine!”. Jack London
Chilo advised, "not to speak evil of the dead." Diogenes Laërtius
Don't speak evil of someone if you don't know for certain, and if you do know ask yourself, why am I telling it? Johann Kaspar Lavater
There is so much good in the worst of us, and so much bad in the best of us, it doesn't behoove any of us to speak evil of the rest of us. Edgar Cayce
Whoever speaks evil to you of others will speak evil of you to others. Kurdish Proverb