While this command echoes King Benjamin's declaration that he had supported himself with is own labor (Mosiah 2:14), this command comes more directly as a counterpoint to the principles on which Noah's priesthood (as an organization, not meaning authority here) was organized. Noah's priests had clearly accumulated wealth at the expense of the people (Mosiah 11:4-6). Alma was directly reacting against that kind of a socially segregated priestly class. He would have priests as teachers, not priests as superiors.