Rashi on Ecclesiastes 7:6:2

תַּחַת הַסִּיר. תַּחַת סִיר נְחשֶׁת הַכָּפוּי עַל תַּבְעֵרַת קוֹצִים, וְהֵם מְקַשְׁקְשִׁים לְתוֹכָהּ. אָמַר רַבִּי יְהוֹשֻׁעַ בֶּן לֵוִי: כָּל קִיסַיָּא, כַּד אִינוּן דָּלְקִין, לֵית קָלְהוֹן אָזִיל. בְּרַם, הָלֵין סִירַיָּתָא, קָלְהוֹן אָזִיל, לְמֵימָר, אַף אֲנָן מִן קִיסַיָּא. מוֹדִיעִים שֶׁאַף אָנוּ מִן הָעֵצִים, וְיֵשׁ צוֹרֶךְ בָּנוּ. אַף הַכְּסִילִים מַרְבִּים דְּבָרִים, לוֹמַר: "גַּם אָנוּ מִן הַחֲשׁוּבִים": Under a pot. Under a copper pot turned over a fire of thorns, and they rattle into it.¹⁸The crackling of thorns in the fire lasts only a brief moment and then is gone. So, too, the laughter of the fool has no useful purpose or lasting value. Or, the verse conveys the thought that the wise grieve because they are fearful that they are lacking in their service to God, whereas fools are generally satisfied and happy because they feel they have totally fulfilled their obligation in their service to God. Rabbi Yehoshua the son of Leivi said, that all [other] woods when they are kindled, their sound does not travel [far], but when thorns are kindled, their sound travels [far], as if to say, “We, too, are of wood”. They publicize, “We too are wood, and we are needed.” So do fools speak excessively, [as if] to say, “We, too, are important.”