XXII. The Bearers of the Trust of God are made manifest unto the peoples of the earth as the Exponents of a new Cause and the Revealers of a new Message. Inasmuch as these Birds of the celestial Throne are all sent down from the heaven of the Will of God, and as they all arise to proclaim His irresistible Faith, they, therefore, are regarded as one soul and the same person. For they all drink from the one Cup of the love of God, and all partake of the fruit of the same Tree of Oneness. (50:1)
These Manifestations of God have each a twofold station. One is the station of pure abstraction and essential unity. In this respect, if thou callest them all by one name, and dost ascribe to them the same attributes, thou hast not erred from the truth. Even as He hath revealed: "No distinction do We make between any of His Messengers." For they, one and all, summon the people of the earth to acknowledge the unity of God, and herald unto them the Kawthar of an infinite grace and bounty. They are all invested with the robe of prophethood, and are honored with the mantle of glory. Thus hath Muhammad, the Point of the Qur'an, revealed: "I am all the Prophets." Likewise, He saith: "I am the first Adam, Noah, Moses, and Jesus." Similar statements have been made by Imam Ali. Sayings such as these, which indicate the essential unity of those Exponents of Oneness, have also emanated from the Channels of God's immortal utterance, and the Treasuries of the gems of Divine knowledge, and have been recorded in the Scriptures. These Countenances are the recipients of the Divine Command, and the Day Springs of His Revelation. This Revelation is exalted above the veils of plurality and the exigencies of number. Thus He saith: "Our Cause is but One." Inasmuch as the Cause is one and the same, the Exponents thereof also must needs be one and the same. Likewise, the Imams of the Muhammadan Faith, those lamps of certitude, have said: "Muhammad is our first, Muhammad is our last, Muhammad our all."
Gleanings from Writings - Bahá'u'lláh