Mischna zu Tehillim 58:6

They [each] said three things: Rabbi Eliezer said: Let the honor of your friend be as dear to you as your own; And be not easily provoked to anger; And repent one day before your death. And [he also said:] warm yourself before the fire of the wise, but beware of being singed by their glowing coals, for their bite is the bite of a fox, and their sting is the sting of a scorpion, and their hiss is the hiss of a serpent, and all their words are like coals of fire.