The Noblest Type of Knowledge In The Qur’aan
The knowledge of Tawheed is the noblest aspect of knowledge without exception. It is the most virtuous and perfect. By way of it the hearts are nurtured upon a sound creed. By way of it, moral character is purified and deeds are perfected. The subject matter of Tawheed is based on the following:
To study what is obligatory to affirm for Allaah regarding His perfect Attributes and lofty descriptions, and that which makes it impossible to either describe Allaah with deficient and blameworthy attributes, or likening Him to others.
To study that which establishes the fact that Allaah alone brought about all things into 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.
[Source: Fat-hul Raheem Al-Malikil Allaam Fee Ilmil Aqaa-id Wat-Tawheed Wal-Akhlaaq Wal-Ahkaam of Imaam Sadi (rahimahullaah). Page:7 Abridged & slightly paraphrased]