Reference for Pirkei Avot 6:5
אַל תְּבַקֵּשׁ גְּדֻלָּה לְעַצְמְךָ, וְאַל תַּחְמֹד כָּבוֹד, יוֹתֵר מִלִּמּוּדְךָ עֲשֵׂה, וְאַל תִּתְאַוֶּה לְשֻׁלְחָנָם שֶׁל מְלָכִים, שֶׁשֻּׁלְחָנְךָ גָדוֹל מִשֻּׁלְחָנָם, וְכִתְרְךָ גָדוֹל מִכִּתְרָם, וְנֶאֱמָן הוּא בַּעַל מְלַאכְתְּךָ שֶׁיְּשַׁלֵּם לְךָ שְׂכַר פְּעֻלָּתֶךָ:
Torah is greater than priesthood and than kingship. For kingship is acquired with thirty eminences and priesthood with twenty-four, whereas Torah is acquired with forty-eight. They are: learning, the hearing of the ear, the articulation of the lips, the understanding of the heart, intuition, awe, fear, humility, joy, attendance upon the wise, the probing of the friends, the dialectics of the disciples, with deliberation, with Scripture, with Mishnah, with diminution of trade, of sleep, of pleasure, of laughter, (and) of cohabitation, with patience, with forbearance, with a good heart, with faith in the sages, and with the acceptance of afflictions.