Concerning the Hidden Words of Bahá'u'lláh
Therefore, there is need of turning back to the original foundation [established by the heavenly Educators]. The fundamental principles of the Prophets are correct and true. The imitations and superstitions which have crept in are at wide variance with the original precepts and commands. Bahá’u’lláh has revoiced and reestablished the quintessence of the teachings of all the Prophets, setting aside the accessories and purifying religion from human interpretation. He has written a book entitled the Hidden Words. The preface announces that it contains the essences of the words of the Prophets of the past, clothed in the garment of brevity, for the teaching and spiritual guidance of the people of the world. Read it that you may understand the true foundations of religion and reflect upon the inspiration of the Messengers of God. It is light upon light.

('Abdu'l-Bahá, The Promulgation of Universal Peace, p. 86)