Ibn Nadeem (died 380 AH) writes in his knowledge-packed offering, Al-Fihrist:
A short time later a son of Naubakht family and a great intellectual of School of Ahlul Bayt, Abu Sahal Ibn Ali (died 311 AH), made a distinct addition to the “Doctrines of Fiqh” by writing Al-khusus wal-Umoom and Abtalul Qias. Then his talented nephew, Abu Muhammad Hasan Ibn Musa Naubakhti, took over the job of preaching and in addition to many other books wrote the most valuable Alkhabrul Wahid wal Amal Beh. It should be kept in mind that Hasan Ibn Musa had the honor of meeting Imam Hasan Askari (as).
Now the short occultation of Last Imam (as) is about to end. This was a time when the scholars (ulama) had the opportunity to work on traditions, commentary, character and morals. Researchers (fuqaha) got a chance to focus on researching the answers to new problems and issues with full freedom and confidence. And other thinkers and intellectuals were able to use their minds for securing and strengthening the religion. This period also taught those, who were associated with Ahlul Bayt, the ways of waiting for the Last Imam (as).