The Báb asked “every loyal adherent of the Faith” to “’hasten to the Land of Khá,’ the province of Khurásán”

In pursuance of the Divine decree, in the days when Quddús was still residing in Mashhad, there was revealed from the pen of the Báb a Tablet addressed to all the believers of Persia, in which every loyal adherent of the Faith was enjoined to “hasten to the Land of Khá,” the province of Khurásán. The news of this high injunction spread with marvellous rapidity and aroused universal enthusiasm. It reached the ears of Táhirih, who, at that time, was residing in Karbilá and was bending every effort to extend the scope of the Faith she had espoused. 

- Nabil (‘The Dawn-Breakers’ chapter 15)

The Báb “summond” “those twin great lights” -Quddús and Táhirih – “to hasten to the land of Tá, the day-spring of glory, the home of Bahá’u’lláh…to seek His advice, to reinforce His efforts, and to prepare the way for His coming Revelation.”

The hand of Omnipotence, however, was busily engaged, at a time when the host of evil-doers were darkly plotting against Him, in confounding their schemes and in nullifying their efforts. In the easternmost province of Persia, the Almighty had, through the hand of Quddús, lit a fire that glowed with the hottest flame in the breasts of the people of Khurásán. And in Karbilá, beyond the western confines of that land, He had kindled the light of Táhirih, a light that was destined to shed its radiance upon the whole of Persia. From the east and from the west of that country, the voice of the Unseen summoned those twin great lights to hasten to the land of Tá, the day-spring of glory, the home of Bahá’u’lláh. He bade them each seek the presence, and revolve round the person of that Day-Star of Truth, to seek His advice, to reinforce His efforts, and to prepare the way for His coming Revelation. 

- Nabil (‘The Dawn-Breakers’ chapter 15)

The “blazed forth in the heart of Khurásán…caused such a conflagration in the hearts of men that the effects of its quickening power were felt in the most outlying provinces of Persia.”

As the appointed hour approached when, according to the dispensations of Providence, the veil which still concealed the fundamental verities of the Faith was to be rent asunder, there blazed forth in the heart of Khurásán a flame of such consuming intensity that the most formidable obstacles standing in the way of the ultimate recognition of the Cause melted away and vanished.  That fire caused such a conflagration in the hearts of men that the effects of its quickening power were felt in the most outlying provinces of Persia. It obliterated every trace of the misgivings and doubts which had still lingered in the hearts of the believers, and had hitherto hindered them from apprehending the full measure of its glory. The decree of the enemy had condemned to perpetual isolation Him who was the embodiment of the beauty of God, and sought thereby to quench for all time the flame of His love. 

- Nabil (‘The Dawn-Breakers’ chapter 15)

The Cause “spread more rapidly in Khurásán than it had anywhere else”

“It will surprise no one to learn,” writes Clement Huart, “that the new sect spread more rapidly in Khurásán than it had anywhere else. Khurásán has been singularly fortunate in that she has always offered to new ideas the most propitious field. It is out of this province that came many evolutions which caused fundamental changes in the Muhammadan Orient. It is enough to recall that in Khurásán the idea of the Persian renovation originated after the Arabian conquest. It was there likewise that the army was organized which, under the orders of Abú-Muslim placed the Abbassides upon the throne of the Khalífs by overthrowing the aristocracy of Mecca which had occupied it since the accession of the Umayyads.” 

(“La Religion de Báb,” pp. 18–19.; Footnotes to chapter 15 of ‘The Dawn-Breakers’, provided by Shoghi Effendi)

“The house of Bábíyyih” became a center to give “rise to a wave of enthusiasm which swept over the entire city of Mashhad”

Shortly after it was completed, Quddús arrived at Mashhad and abode in that house. A steady stream of visitors, whom the energy and zeal of Mullá Husayn had prepared for the acceptance of the Faith, poured into the presence of Quddús, acknowledged the claim of the Cause, and willingly enlisted under its banner. The all-observing vigilance with which Mullá Husayn laboured to diffuse the knowledge of the new Revelation, and the masterly manner in which Quddús edified its ever-increasing adherents, gave rise to a wave of enthusiasm which swept over the entire city of Mashhad, and the effects of which spread rapidly beyond the confines of Khurásán. The house of Bábíyyih was soon converted into a rallying centre for a multitude of devotees who were fired with an inflexible resolve to demonstrate, by every means in their power, the great inherent energies of their Faith. 

- Nabil (‘The Dawn-Breakers’ chapter 14)

Mullá Husayn completed his assignment from Quddús: a house named Bábíyyih was built in Mashhad

Alone and with a heart wholly detached from all else but God, Mullá Husayn set out on his journey to Mashhad. His only companion, as he trod his way to Khurásán, was the thought of accomplishing faithfully the wishes of Quddús, and his one sustenance the consciousness of his unfailing promise. He went directly to the home of Mírzá Muhammad-Báqir-i-Qá’iní, and was soon able to buy, in the neighbourhood of that house in Bálá-Khiyabán, a tract of land on which he began to erect the house which he had been commanded to build, and to which he gave the name of Bábíyyih, a name that it bears to the present day. 

- Nabil (‘The Dawn-Breakers’ chapter 14)