Reference for Pirkei Avot 4:11
רַבִּי אֱלִיעֶזֶר בֶּן יַעֲקֹב אוֹמֵר, הָעוֹשֶׂה מִצְוָה אַחַת, קוֹנֶה לוֹ פְרַקְלִיט אֶחָד. וְהָעוֹבֵר עֲבֵרָה אַחַת, קוֹנֶה לוֹ קַטֵּגוֹר אֶחָד. תְּשׁוּבָה וּמַעֲשִׂים טוֹבִים, כִּתְרִיס בִּפְנֵי הַפֻּרְעָנוּת. רַבִּי יוֹחָנָן הַסַּנְדְּלָר אוֹמֵר, כָּל כְּנֵסִיָּה שֶׁהִיא לְשֵׁם שָׁמַיִם, סוֹפָהּ לְהִתְקַיֵּם. וְשֶׁאֵינָהּ לְשֵׁם שָׁמַיִם, אֵין סוֹפָהּ לְהִתְקַיֵּם:
R. Eliezer ben Yaakov says: If one does one mitzvah, he acquires for himself one defense attorney [i.e., an angel speaking on his behalf.] And if one commits a sin, he acquires for himself one kategor (a prosecuting attorney), [i.e., an incriminating angel, (kategor being acronymic for "kore tigar," "calling out strife." Sanegor, the opposite of kategor is acronymic for "sone tigar," "hating strife.")] R. Yochanan Hasandlar says: Every gathering that is for the sake of Heaven is destined to endure, and (every gathering that is) not for the sake of Heaven is not destined to endure.