Piety is the eternal lesson that His Holiness Ali-ibn-Abitaleb (peace and greetings be upon him) taught to all human generations in words and in practice. Piety means constant watchfulness of one's words, deeds, thoughts and intentions... Thus, our worldly progress and welfare and also our salvation in the hereafter are all contingent on piety. This is the lesson taught to us by the Commander of the Faithful (peace and greetings be upon him).