His travels and public preaching were instrumental in spreading the religion throughout Persia, allowing him to come into contact with many prominent clerics and government officials, including Baháʼu'lláh and Mohammad Shah Qajar.

Mullá Husayn is regarded as a significant martyr in Bábism and the Baháʼí Faith and accorded a high spiritual station in both religions as the first to believe in the Báb and a prominent participant in the perceived fulfillment of many elements of Islamic eschatology.

Although he would later distinguish himself as a military leader, and traverse the entirety of Persia on foot multiple times, Mullá Husayn is reported to have been in poor health from a young age.

A critic of the Bábí movement suggested that he received early training in swordsmanship, while childhood friends deny this, indicating he often had difficulty even with the physical exertion involved in lengthy writing sessions as a student and in his later work as a scribe and copyist.

[5]At the age of twelve he left school and pursued higher education in the madrasa (seminary) of Mashhad and Isfahan–which included lessons in Persian literature and the Qurʼan–while working to master the art of debate.

Scholars have suggested that his family members practiced Ismaʻili Shiʻism, but in Mashhad and Isfahan he studied Muslim theology and jurisprudence under prominent teachers from the Usuli school.

[7] By 21, he had been licensed as an Usuli mujtahid (cleric), granting him the publicly recognized right to preach in mosques, take on students of theology, and issue fatwas (authoritative legal opinion).

During his studies in Mashhad he became attracted to the teachings of the Shaykhi school of Shia Islam, founded by Shaykh Ahmad Ahsá'í and led at the time by his successor, Siyyid Kázim Rashtí.

[12] Mullá Husayn studied under Siyyid Kázim from 1835 until 1843, during which time he was often asked by his teacher to travel to Persia to debate publicly with orthodox Shia ulama to gain more widespread Persian support for Shaykism.

[16] Baháʼí sources traditionally suggest that Siyyid Kázim entrusted Mullá Husayn with secret teachings which he did not share with the larger body of Shaykis—a claim which is evocative of his later role in Bábism, but difficult to verify.

[18][19]Mullá Husayn, accompanied by his brother Muhammad-Hasan and nephew Muhammad-Baqir, set off from Karbala to Najaf and spent forty days in the Great Mosque of Kufa sequestered in a state of prayer and fasting.

Mullá Husayn is reported to have publicly burst into tears upon reading the posthumous instructions of Siyyid Kázim and realizing the enormity and uncertainty to his task.

After celebrating the Muslim holiday of Mawlid, marking the completion of forty days spent at the Great Mosque of Kufa, Mullá Husayn and his companions visited the Tomb of the Imam Ali in Najaf and proceeded toward Búshihr, on the Persian Gulf.

[24] At this point they had traveled on foot for approximately 600 miles with no clear intended destination and no guide for their journey except Siyyid Kázim's dying advice to Mullá Husayn.

[43] In the writings of the Báb as well as later Baháʼí hagiography, the example of the first Isfahani Bábí, a wheat sifter of modest means, is often used as an example of the diversity of those who accepted the Báb's teachings and the corruption of the Persian religious elites: In the land of Sád [Iṣfahán], which to outward seeming is a great city, in every corner of whose seminaries are vast numbers of people regarded as divines and doctors, yet when the time came for inmost essences to be drawn forth, only its sifter of wheat donned the robe of discipleship.

As in Isfahan, he was opposed by members of the remaining Shayki community who felt he had abandoned his role as a leading follower of Siyyid Kázim to take up membership in a heretical sect.

Gobineau reports that in spite of not preaching publicly in Tehran, Mullá Husayn was received by a number of prominent residents, including the king Mohammad Shah Qajar and his prime minister and shared the teachings and writings of the Báb with them in these private meetings.

Mullá Husayn learned that the leader of the rebellion hoped to secure his support as a representative of the growing Bábi community, and decided on leaving Mashhad to avoid entangling the local Bábís in the chaos expected to result when the forces of the Shah eventually arrived.

[57] Mullá Husayn stayed in Maku with the Báb for nine days,[58] during which accounts report that the two cherished each other's company in the relative peace of imprisonment in a remote province.

With the assistance of local Bábís he purchased a plot of land and erected a building intended to serve as a permanent residence for himself and Quddús as well as a center of Bábí preaching and community life.

[68] This period yielded a great deal of success for Mullá Husayn and Quddús, Bábí communities sprouted throughout Khorasan Province, including converts from a wide array of economic backgrounds.

[69] A few months after the construction of the Bábíyyih, a large number of Bábís gathered in the village of Badasht for the purpose of seeking consensus on the core spiritual beliefs of Bábism and making plans for how the Bábí community should respond to increasing persecution and the continued imprisonment of the Báb.

[72] As the number of converts in Mashhad began to grow, opposition from secular and religious authorities increased to the point that Mullá Husayn was forced to leave the city before Quddús could return from Badasht.

Further, Mullá Husayn was, in apparent fulfillment of Islamic eschatological predictions, to don the Báb's own green turban, and lead his companions under a black flag.

[84] The distribution of urban and rural participants has been shown to be roughly identical to the makeup of Persian society at the time, demonstrating the wide array of respondents to the religion of the Báb.

ʻAbdu'lláh Khán and his officers took up residence in a nearby village to avoid the weather, and were absent when, on the fourth day of the siege, Quddús ordered the Bábís to disperse his army.

[91] After this point, the fort walls reached ten meters tall, with a deep ditch surrounding it, a well for water, and tunnels and storehouses dug underground for refuge and storage.

Mullá Husayn repudiated the accusation of rebellion and claimed that they had no intention except to oppose the corruption of the ecclesiastical order of the country through debate and preaching the message of the Báb.

[99]Initially the Bábí thrust was successful in sowing confusion in the ranks of Abbás-Qulí Khán's troops, and a significant number of their tents and barricades were burnt to the ground.

His raising of the Black Standard prior to the battle of Fort Tabarsi is seen as the fulfillment of Shia eschatological predictions, and further cements his station as an important part of Bábí and Baha'i claims of Mahdi-hood for the Báb.