If a man possess merit, the merit speaks for itself, not the owner of the merit.
If thou hast not the purest musk, claim not to possess it; if thou hast, it makes itself known by its perfume.
Discourse on Slander
Speak no evil concerning the good or the wicked, for thus thou wrongest the former and makest an enemy of the latter.
Know that he who defames another revealeth his own faults.
If thou speak evil of any one, thou art sinful, even though what thou sayest be true.
Story concerning the same Subject
To one who stretched his tongue in slander, a wise man said: “Speak not evil of any one before me, so that I may not think ill of thee. Although his dignity is lowered, thine own honour is not increased thereby.”