Mishnah for Pirkei Avot 1:17
שִׁמְעוֹן בְּנוֹ אוֹמֵר, כָּל יָמַי גָּדַלְתִּי בֵין הַחֲכָמִים, וְלֹא מָצָאתִי לַגּוּף טוֹב אֶלָּא שְׁתִיקָה. וְלֹא הַמִּדְרָשׁ הוּא הָעִקָּר, אֶלָּא הַמַּעֲשֶׂה. וְכָל הַמַּרְבֶּה דְבָרִים, מֵבִיא חֵטְא:
Shimon, his son, says: All my days I have grown up among the wise, and I have found nothing better for (my) body than silence [i.e., hearing myself shamed and remaining silent.] And it is not the expounding which is primary but the act [i.e., and know that silence is good, for even for expounding and speaking in Torah, than which there is nothing greater, the primary reward is for the act (which follows from it); and if one expounds and does not act (upon what he says), it would be better if he remained silent and did not expound.] And all who increase words bring sin. [For thus do we find with Eve, who "increased words" in saying (Genesis 3:3): "G-d said: 'You shall not eat of it and you shall not touch it.'" She added "touching," which had not been forbidden to her, and the serpent pushed her until she touched it. And he said to her: "Just as there is no death in touching it, so there is no death in eating it." And this led to her sin of eating from the fruit. As Solomon says (Proverbs 20:6): "Do not add to His words, lest He reprove you and you be proven false."]