Abu Ja'far Muhammad bin Yaqoub bin Ishaaq al-Kulainy Ar-Razi (d.328/329 h), sometimes honoured with the title "Thiqatul-Islam" (Trust of Islam) is the famous Shia author of Usul al-Kafi For other uses, including people named Islam, see Islam (disambiguation). ... Shiʻa Islam (Arabic شيعى follower; English has traditionally used Shiite) makes up the second largest sect of believers in Islam, constituting about 30%–35% of all Muslim. ... Usul al-Kafi is one of the most authoritarian Shia hadith collections, collected by Muhammad Yaqub Kulainy. ...