And indeed, the utmost good is for the one to whom Allaah grants understanding of the Religion And it is enough ignorance for a person that he does not know about his Religion. Such a person is passionately addicted to pleasures, accustomed to following desires, or is one given to amassing wealth and piling it up. Such people are not from the callers to the Religion rather they are more like the grazing cattle. And thus knowledge passes away with the passing away of those who carry it.
— Ali (radhiAllahu ‘anhu) [Reported by Abu Nu'aym in Hilyatul-Awliyaa (1/79-80), al-Khateeb al-Baghdaadee in al-Faqeeh wal-Mutafaqqih (1/49-50) and Ibn Katheer in al-Bidaayah wan-Nihaayah (9/47)]