Masjid Abdullah Bin Mas'ud is a mosque in Cleveland, Ohio, centered on disciplined Islamic learning and principled worship. Its religious instruction emphasizes usool, or first principles, with a strong focus on core texts, orthodox Sunni foundations, creed, methodology, and adherence to the Sunnah. Themes such as "Foundations of the Sunnah" and "Back to Basics" reflect a methodical approach to essential religious knowledge, shaping an atmosphere of seriousness, doctrinal clarity, and steady formation in belief, worship, and conduct.