Chagiga 13 - 19
“If the Rav seems to you as a malach (agent) of G-d, then seek to learn Torah from him; but if not, then do not learn from him.”
Rabbah bar Bar Chana teaches this on our daf in the name of Rabbi Yochanan to explain the verse that states: “Because the lips of the Kohen guard wisdom and Torah; seek it from his mouth, because he is the malach of the L-rd of Hosts (Malachi 2:7).” The Maharsha points out that the Kohanim, from the Tribe of Levi, were traditionally the teachers of Torah to the Jewish people and that is why the word “Kohen” is specifically mentioned in the verse cited. Only if the potential teacher is a Rav who is also “kosher” in his deeds – aside from his greatness in Torah – then seek to learn Torah from him.
- Chagiga 15b
Rabbi Yehuda ben Rabbi Nachmeini said, "If the ‘evil inclination’ tries to persuade you to sin by assuring you that G-d will forgive you anyway, don't listen to him!"
- Chagiga 16a