Abdul-Qadir Gilani
The most important scholars of almost all of the Islamic sects and schools of thought were Persian or lived in Iran, including the most notable and reliable Hadith collectors of Shia and Sunni like Shaikh Saduq, Shaikh Kulainy, Hakim al-Nishaburi, Imam Muslim and Imam Bukhari, the greatest theologians of Shia and Sunni like Shaykh Tusi, Imam Ghazali, Imam Fakhr al-Razi and Al-Zamakhshari, the greatest physicians, astronomers, logicians, mathematicians, metaphysicians, philosophers and scientists like Avicenna, and Nasīr al-Dīn al-Tūsī, the greatest Shaykh of Sufism like Rumi, Abdul-Qadir Gilani.