According to Imam Khomeini, the law of Islam, and the divine command has absolute authority over all individuals and the Islamic government. Everyone, including the Most Noble Messenger and his successors, is subject to law and will remain so for all eternity—the law that has been revealed by God, Almighty and Exalted, and expounded by the tongue of the Qur’an and the Most Noble Messenger.
If the Prophet (PBUH) assumed the task of divine viceregency upon earth, it was in accordance with divine command.
God, Almighty and Exalted, appointed him as His viceregent, “the viceregent of God upon earth”; he did not establish a government on his own initiative in order to be leader of the Muslims, the leader of contemporary Muslim world explained.
Similarly, when it became apparent that disagreements would probably arise among the Muslims because their acquaintance with the faith was recent and limited, God the Almighty charged the Prophet, by way of revelation, to clarify the question of succession immediately, there in the middle of the desert.
Then the Most Noble Messenger (pbuh), nominated the Commander of the Faithful ('a) as his successor, in conformity and obedience to the law, not because he was his own son-in-law or had performed certain services, but because, he was acting in obedience to God’s law, as its executor.
In Islam, then, government has the sense of adherence to law; it is law alone that rules over society.
Even the limited powers given to the Most Noble Messenger and those exercising rule after him have been conferred upon them by God.
Whenever the Prophet expounded a certain matter or promulgated a certain injunction, he did so in obedience to divine law, a law that everyone without exception must obey and adhere to.
Divine law obtains both for the leader and the led; the sole law that is valid and imperative to apply is the law of God.
Obedience to the Prophet also takes place in accordance with divine decree, for God says: “And obey the Messenger”(Qur’an, 4:59). Obedience to those entrusted with authority is also on the basis of divine decree: “And obey the holders of authority from among you.” (Qur’an, 4:59)