Rav has no portion in World to Come

  Making of a Godol (pages 670-671) Upon hearing of a certain man's plans to become a shohet, R' Laib told him, "A shohet? Are you unaware that  Avos de\Rabbi Nosson (36:5) lists a shohet among the seven who have no share in the World to Come'?!" The luckless fellow then said he would have to look for an alternate occupation. But R' Laib stopped him and said, "No, no, go ask the rav. Another of the seven is a rav, and he must have found some dispensation which may apply to you, too." [Another of my father's talmidim, present at the time, asked him what then was the heter for becoming a rav, and he replied, "When I took the job in Tzitevian,I thought to myself that if there were someone in the town better able to rule on halakhic problems than myself, I would resign, and if not, I was obliged to be the rav' ([My father meant to say that an obligation overrides the World to Come consideration.])

Avos de\Rabbi Nosson (36:5) שבעה אין להם חלק לעוה״ב ואלו הן לבלר וסופר וטוב שברופאין ודיין לעירו וקוסם חזן וטבח: 

Shabbos (139a) It was taught in a baraita that Rabbi Yosei ben Elisha says: If you see a generation that many troubles are befalling it, go and examine the judges of Israel. Perhaps their sins are the cause, as any calamity that comes to the world comes due to the judges of Israel acting corruptly, as it is stated: “Please hear this, heads of the house of Jacob, and officers of the house of Israel, who abhor justice and pervert all equity, who build up Zion with blood, and Jerusalem with iniquity. Their heads they judge for bribes, and their priests teach for hire, and their prophets divine for money; yet they lean upon the Lord, saying: Is not the Lord in our midst? No evil shall befall us” (Micah 3:9–11).