'RYishmael, son of [R' Yochanan ben Beroka], says: One who studies [Torah] in order to teach is given the means to study and to teach; but one who studies [Torah] in order to practice is given the means to study and to teach, to observe and to practice.  R' Tzadok says: Do not make [the words of Torah] into a crown in order to be glorified through them; nor a spade with which to dig.  So too, Hillel used to say: And one who makes use of the crown will pass [away]. From this you derive: whoever seeks personal benefit from the words of Torah removes his life from the world.