Mishnah 20 - Chapter 5 - Pirkei Avot

Yehudah ven teima omer. Hevei az kannamer, vekal kannesher, veratz katzevi, vegibbor ka'ari la'asot retzon avicha shebbashamayim. Hu hayah omer, az panim legeihinnam, vvoshet panim legan eden. Yehi ratzon millefaneicha hashem eloheinu shettivneh irecha bimherah veyameinu veten chelkenu betoratecha.

Judah ben Tema said: Be strong as a leopard, and swift as an eagle, and fleet as a gazelle, and brave as a lion, to do the will of your Father who is in heaven. He used to say: the arrogant is headed for Gehinnom and the blushing for the garden of Eden. May it be the will, O Lord our God, that your city be rebuilt speedily in our days and set our portion in the studying of your Torah.

Yehudah ben Tema says: Be audacious as a leopard, […and do not be ashamed to ask your Rabbi what you have not understood, as we have learned: "The shy one does not learn"], and light as an eagle [to pursue your learning and not weary, as it is written (Isaiah 40:31): "They will lift the wing like eagles; they will run and not weary"], and swift as a deer [to pursue mitzvoth], and strong as a lion [to subdue your evil inclination against transgressing], to do the will of your Father in Heaven. He was wont to say: "The 'brazen-faced' to Gehinnom" [This expression is used because brazenness is seen in the face, viz. (Proverbs 21:19): "The wicked man is brazen in his face"], and the 'shame-faced' to Gan Eden." May it be Your will, O L rd our G-d that You build Your city hastily in our days and give (us) our portion in Your Torah. [That is, just as You have granted us this trait (of shame-facedness), the signs of the seed of Abraham being shame-facedness, mercy, and lovingkindness, so, may it be Your will, etc.]