Avot4: 7
רַבִּי יִשְׁמָעֵאל בְּנוֹ אוֹמֵר, הַחוֹשֵׂךְ עַצְמוֹ מִן הַדִּין — פּוֹרֵק מִמֶּנּוּ אֵיבָה וְגָזֵל וּשְׁבוּעַת שָׁוְא. וְהַגַּס לִבּוֹ בְהוֹרָאָה — שׁוֹטֶה רָשָׁע וְגַס רוּחַ.
'RYishmael, son of [R' Yose], says: One who withdraws from judgment removes from himself hatred, robbery, and [the re-sponsibility for] an unnecessary oath; but one who is too self-confident in issuing legal decisions is a fool, is wicked, and is ar-rogant of spirit.