The Foundation of the Sunnah and the Creed of the Religion

The Salaf (may Allāh have mercy on them) have enormous efforts in this tremendous arena. They have great actions, and service to the Aqeedah, aiding it, and establishing the significant obligations towards it. They have written hundreds, of books clarifying and explaining it, with proofs and evidence. Rather they have authored thousands of books; some are lengthy while some are concise; some are complete in describing every facet while some are limited to a particular subject matter. Some of these books lay the foundation for the truth and that which is correct while others refute those who oppose.