Imam Musa b. Ja'far al-Kazim peace be upon himأفْضَلُ العِبادَةِ بَعْدَ المَعْرِفَةِ انْتِظارُ الفَرَجِ The most virtuous deed, after Knowing Allah, is waiting for Appearance (of Imam Mahdi peace be upon him). Tuhaf al-Uqul, page 403 ...