The only basis and principle upon which the Holy Prophet (S) laid the foundation of his religion is the principle of Tawhid

"The only basis and principle upon which the Holy Prophet (S) laid the foundation of his religion is the principle of Tawhid which he recognized as the source of the prosperity for the people of the world. According to the principle of Tawhid only Allah is the Creator of the world and worthy of being worshipped. We must not bow down and pay homage to anyone except the Almighty Allah. Thus the principle that must be practiced in human societies is for all to act like brothers and be equal with one another and not to regard anyone as their unconditional sovereign except Allah."

ALLAMA TABATABAI (R)