“I once heard abu ‘Abd Allah (a.s.), saying, ‘The Messenger of Allah, O Allah, grant compensation to Muhammad and his family worthy of their services to Your cause, said, when he was about to leave this world to Ali (a.s.), “O Ali, you must not allow that farmers be oppressed before you; and you must not allow taxes on land to increase and you must not allow free labor on a Muslim” (meaning free labor when he is hired).”’