הֵם אָמְרוּ שְׁלשָׁה דְבָרִים. רַבִּי אֱלִיעֶזֶר אוֹמֵר, יְהִי כְבוֹד חֲבֵרְךָ חָבִיב עָלֶיךָ כְּשֶׁלָּךְ, וְאַל תְּהִי נוֹחַ לִכְעֹס. וְשׁוּב יוֹם אֶחָד לִפְנֵי מִיתָתְךָ. וֶהֱוֵי מִתְחַמֵּם כְּנֶגֶד אוּרָן שֶׁל חֲכָמִים, וֶהֱוֵי זָהִיר בְּגַחַלְתָּן שֶׁלֹּא תִכָּוֶה, שֶׁנְּשִׁיכָתָן נְשִׁיכַת שׁוּעָל, וַעֲקִיצָתָן עֲקִיצַת עַקְרָב, וּלְחִישָׁתָן לְחִישַׁת שָׂרָף, וְכָל דִּבְרֵיהֶם כְּגַחֲלֵי אֵשׁ

 

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.

Pirkei Avot 2:10