Center of the Covenant

As to the most great characteristic of the revelation of Bahá’u’lláh, a specific teaching not given by any of the Prophets of the past: It is the ordination and appointment of the Center of the Covenant.
By this appointment and provision He has safeguarded  and protected the religion of God against differences and schisms, making it impossible for anyone to create a new sect or faction of belief. To ensure unity and agreement He has entered into a Covenant with all the people of the world, including the interpreter and explainer of His teachings, so that no one may interpret or explain the religion of God according to his own view or opinion and thus create a sect founded upon his individual understanding of the divine Words.
The Book of the Covenant or Testament of Bahá’u’lláh is the means of preventing such a possibility, for whosoever shall speak from the authority of himself alone shall be degraded. Be ye informed and cognizant of this....

`Abdu'l-Bahá: The Promulgation of Universal Peace P. 456