It was in Adrianople that Bahá'u'lláh revealed a Tablet the significance of which cannot be over-estimated. That Tablet was the Suriy-i-Ghusn (Surih of the Branch) addressed to Mirza 'Ali-Riday-i-Mustawfi, a Bahá'í of Khurasan --that province in eastern Persia famed in the Bábí Dispensation and to which some momentous prophecies of Bahá'u'lláh specifically apply. Mirza 'Ali-Rida was a high-ranking official in the service of the government, and his brother, Mirza Muhammad-Rida …also a follower of Bahá'u'lláh, was the Vizier of Khurasan. In the Suriy-i-Ghusn, Bahá'u'lláh thus extols His eldest Son:
“There hath branched from the Sadratu'l-Muntaha this sacred and glorious Being, this Branch of Holiness; well is it with him that hath sought His shelter and abideth beneath His shadow. Verily the Limb of the Law of God hath sprung forth from this Root which God hath firmly implanted in the Ground of His Will, and Whose Branch hath been so uplifted as to encompass the whole of creation. Magnified be He, therefore, for this sublime, this blessed, this mighty, this exalted Handiwork I . . . A Word hath, as a token of Our grace, gone forth from the Most Great Tablet -- a Word which God hath adorned with the ornament of His own Self, and made it sovereign over the earth and all that is therein, and a sign of His greatness and power among its people . . . Render thanks unto God, O people, for His appearance; for verily He is the most great Favour unto you, the most perfect bounty upon you; and through Him every mouldering bone is quickened. Whoso turneth towards Him hath turned towards God, and whoso turneth away from Him hath turned away from My Beauty, hath repudiated My Proof, and transgressed against Me. He is the Trust of God amongst you, His charge within you, His manifestation unto you and His appearance among His favoured servants . . . We have sent Him down in the form of a human temple. Blest and sanctified be God Who createth whatsoever He willeth through His inviolable His infallible decree. They who deprive themselves of the shadow of the Branch, are lost in the wilderness of error are consumed by the heat of worldly desires, and are of those who will assuredly perish.” (Baha’u’llah, quoted by Shoghi Effendi in The Dispensation of Baha’u’llah, pp. 45-46)
(Balyuzi, ‘Abdu'l-Baha - The Centre of the Covenant’)