Zohar

I have heard it said in the name of the Baal Shem Tov that a teacher who does not study Zohar cannot help his students to acquire a holy soul. Only a teacher who studies the Zohar, one who has internalized the inner light and holiness of the Torah, can help his students to make that light and holiness a part of their own souls.

(Rabbi Yaakov Meir Shechter)