590. Commentary: The imam being a hafiz (one who has memorized the Qur'an), a scholar, and a dignified person is extremely effective in the matter of enjoining good and forbidding evil (amr bil ma'ruf wa nahi 'anil munkar); people readily accept their words.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 590