How did the Salaf treat their shaykhs, and what should be done when a scholar enters the mosque?

It was among the practices of the righteous predecessors to revere scholars and respect people of virtue, in compliance with the command of the Messenger of Allah, peace and blessings be upon him, to assign people to their rightful ranks. Imam Abu al-Qasim ibn Asakir warned against slandering scholars, indicating that their flesh is poisoned, and that Allah will expose those who disparage them. Indeed, Islam encourages revering and honoring scholars, because they are the inheritors of the prophets and carry the Law of Allah, and honoring them is an honoring of what they carry.