The problem of earthly world`s supervisors may be considered one of the neglected issues of the Hereafter witnesses. God has taken earthly worlds` supervision as a duty for earthly agents, particularly for prophets and more particularly for the Prophet of Islam and pure Imams. The paper, studying the Quranic word of supervision and its synonymous, commentary views, traditional proofs and contextual indications, has concluded that God has chosen a witness for each nation to oversee its actions. The Prophet of Islam has been known as the supervisor of all nations from the beginning to the end of earthly life. Sunni commentators have viewed witnesses after Prophet`s death to be chosen in the way of consensus, while Shiite commentators has related the supervision to pure Imam. Imams` duty in the field includes all times and it is during their life and death alike.