Yahya bin al-Husayn bin al-Qasim ar-Rassi was born in Medina, being a Sayyid who traced his ancestry from Hasan, son of Ali. His grandfather al-Qasim ar-Rassi, who unsuccessfully tried to reach political leadership, owned a property close to Mecca, ar-Rass. This is the origin of the name of the dynasty founded by Yahya, the Rassids. Al-Qasim ar-Rassi was a major organizer of the theology and jurisprudence of the Zaydiyya division of the Shi’ites, which also had a following in Persia. The Zaydiyya hailed from Zaid, second son of the fourth Shi'a imamZayn al-Abidin. Yahya developed a theology based on his grandfather's teachings but gave it a more pronounced Shia profile. His positions were close to the contemporary Mu'tazila school in Iraq which emphasized reason and rational thinking. In 893 Yahya entered Yemen from the Hijaz, trying to build up a Zaydiyya power base in the area. His ambition was to rid the land from bad religious practices and bring the benefits of his own version of Islam. At this time the Tihamah lowland was ruled by the Ziyadid Dynasty, originally governors of the Abbasid caliphs. In the interior, San'a was dominated by the indigenous Yu’firid Dynasty since 847.
Acknowledged as imam
Yahya's first attempt in 893 was cut short. He reached ash-Sharafah, some distance from San'a, but was then forced to turn back since he did not find the enthusiastic welcome he had hoped for. A new opportunity offered itself three years later. In 896 some tribal leaders from Sa'dah and Khawlan invited Yahya to come back and end the strife-torn conditions of northern Yemen. In the next year 897 he returned from Hijaz together with his uncle Muhammad and other relatives. He reached Sa'dah, where his regime was acknowledged by the population in the region. The new imam adopted the honorific al-Hadi ila'l-Haqq, or al-Hadi for short. The sources portray him as unusually intelligent, physically strong and pious. The new leader was able to subjugate the Najran region, establishing a firm base among the tribal groups of northern Yemen. He took great care to collect taxes according to the religious scriptures, but also to avoid abuses and arbitrary tax harvesting. On the other hand, there was still no formal administrative apparatus or fixed pattern of succession, and in some respects the Zaydi regime was hardly a state at all. The imam had to rely on tribal support, but also did his best to Command the Right and Forbid the Wrong, and to administer Islamic justice and law. The ambitions and limitations of the new Zaydi regime were highlighted by the outdrawn struggle for mastery over the key city San'a. The governor of the city, Abu'l-Atahiyah, grew tired of the Yu’firid faction. He therefore invited al-Hadi to rule over San'a in 899, and acknowledged his status as imam. Al-Hadi entered the city in 901. He struck coins and the khutbah was read in his name. However, fighting soon broke out, and San'a rapidly changed hands between him and the Yu’firid ruler Abd al-Qahir. By this time the imam suffered from poor health, and his tribal supporters were unreliable. Eventually he left the city to its fate in 902, being carried back to Sa'dah in a litter. A new expedition against San’a was undertaken in the next year but led to another defeat. One of al-Hadi's sons was captured by the Yu'firid general.
Death
In a twist of alliances in 906, the imam joined forces with the Yu'firid ruler As'ad, in order to counter Ibn Hawshab and Ali ibn al-Fadl, the clients of the Fatimids. The new alliance soon proved fragile, however. San'a was taken by the Fatimid commander Ali bin al-Fadl who also dominated the Tihamah and the south. Ali soon renounced not only the Fatimids but also Islam itself. Eventually, in 910, al-Hadi resolved to establish his authority over San'a once again. He marched into the city without much opposition but soon left it to the Yu'firids. In the next year the imam died in Sa'dah. According to some, he was poisoned. His tomb is adjacent to the al-Hadi mosque in Sa'dah, which is named after him and one of the oldest buildings of Islamic Yemen. He was succeeded in his dignity by his son al-Murtada Muhammad.
Legacy
Although al-Hadi ila'l-Haqq Yahya was not always a successful ruler, he made a lasting impression on the tribal groups in the Yemeni highland, successfully propagating the Zaydi ideology of Islam – it has actually been argued that it was the Zaydis who seriously introduced Islam in Yemen. Personally, he had the strength, courage and religious knowledge that were a prerequisite for the imamate. He was believed to have fought 70 battles, and was reportedly so strong that he could obliterate the stamp on a coin with his fingers. He saw himself as the restorer of Muslim beliefs, as seen from quotations of his works: "I revived the Book of God after it had perished", or "I revive the Book and the Sunna which have been rejected". Al-Hadi’s religious teachings were in many respects strict, adhering to the school of his grandfather and Zayd bin Ali. He strove for a community where the imam, as the divinely designated leader, ensured the spiritual welfare of the people. For example, he expected women to be veiled, and soldiers to share the spoils in accordance to the Qur’an. He also tried to force the dhimmis of Najran to sell back any land they had bought in the Islamic period, but in the end he had to modify this. Al-Hadi's subjects in the northern highland were not always content with the austere code of conduct that the imam tried to impose. Those who invited him had expected a prestigious mediator in their intratribal conflicts, rather than someone who tried to implement strict Islamic precepts. The career of al-Hadi was therefore turbulent, as he tried to discipline rebellious and ostensibly sinful subjects.
