Miszna do Jozuego 1:20

Rabbi Tarfon said: the day is short, and the work is plentiful, and the laborers are indolent, and the reward is great, and the master of the house is insistent.

Rabbi Akiva said: Merriment and frivolity accustom one to sexual licentiousness; Tradition is a fence to the Torah; Tithes a fence to wealth, Vows a fence to abstinence; A fence to wisdom is silence.

Ben Bag Bag said: Turn it over, and [again] turn it over, for all is therein. And look into it; And become gray and old therein; And do not move away from it, for you have no better portion than it.