The suspicions of the Turks were however raised, and al-Qasim fled San'a, finally setting forth his claim (da'wah) to the imamate in Hajur in the north-west in September 1597.
[2] In his theological thinking al-Mansur al-Qasim upheld the Shia foundations of Zaydiyyah by stressing the eighth-century Jarudi position to the imamate which considered the first two caliphs as usurpers.
He emphasized the differences between Zaydiyyah and the Mu'tazila school of theology, which laid stress on reason and rational thought, whereas some previous Yemeni imams had noted the similarities.
He argued that the early imams had limited their prescriptions to what could be traced to reason, the unambiguous Qur'an text, and the generally accepted Sunnah.
Although the Zaidi imamate is not strictly speaking hereditary, but depends on the qualifications and Sayyid ancestry of the claimant, al-Mansur al-Qasim actually founded a dynasty, known after him as the Qasimids.