'Fuqaha Sabah of Tabieen min-ahl-Medinah', ie. Seven Greatest of Tabieen of 2nd Greatest Generation (Tabieen): 1. Saeed ibn Musayyab, 2. Qasim, 3. Urwah, 4. Kharijah, 5. Sulayman ibn Yasar, 6. Ubaydullah, 7a. Abu Salamah, or 7b. Salim or 7c. Abu Bakr

Allah chose among the greatest of Muslims & Scholars to preserve Hadith of Prophet Muhammed. Here is some inspiring info about the major source compilations of Hadith and its great Scholars & Imams (Bukhari, Muslim, Abu Dawud, Tirmidhi, Nasaee, Ibn Majah, Ahmed ibn Hanbal ...