In The Name of Allaah, The Most Merciful, The Bestower of Mercy
The knowledge of Sound Creed and Fundamental Principles of Tawheed
This is the noblest of all the affairs of knowledge without exception. It is the most virtuous and perfect.By way of it, the hearts are established upon sound creed, and manners are purified and made to flourish. And by way of it, deeds are corrected and made perfect. The subject matter of this affair is based on the following:
Studying what is obligatory to affirm for Allaah regarding His perfect Attributes and lofty descriptions, and that which prevents and makes it impossible for Him to be described with deficient and blameworthy attributes, or making similarities to Him with others.
[Studying] that which establishes the fact that Allaah [alone] brought about all the things in the existence and that He does whatever He wills-whatever He wishes will take place and whatever he does not wish cannot take place.
Likewise, studying what is obligatory regarding belief in the Messengers, their qualities and the rights due to them, and what is forbidden with regards to violation of such rights.
Belief in the Books revealed to the Messengers and in that which Allaah has stated about Himself, and that which His Messengers stated regarding the events of the past and the future.
Belief in the last day, recompense, reward and punishment, the paradise and hell fire, and that which is stated and connected to these affairs.
These are the general affairs of this lofty affair of knowledge. Indeed the Qur’aan has explained these affairs with a profound explanation and clarified it in a manner that is not equal to [its explanation and clarification in] the other revealed books. There is no fundamental affair except that the Qur’aan has explained it.
[Fat-hul Raheem Al-Malikil Allaam Fee Ilmil Aqaa-id Wat-Tawheed Wal-Akhlaaq Wal-Ahkaam of Imaam Sadi (rahimahullaah). Page: 7. Abridged and slightly paraphrased]