Tawhid to single out Allah as the only Creator and Controller (of all that exists), to purify worship for Him alone, to abandon the worship of others besides Him, to affirm that He possesses the Most Beautiful Names and Loftiest Attributes, and to absolve Him of any deficiency or defect.

What are its categories?

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Tawhid ar-Rubūbiyyah (Oneness in Lordship)

This is to single out Allah in His actions, by believing that He Alone is the Creator of all creatures.

ٱللَّهُ خَـٰلِقُ كُلِّ شَىْءٍۖ

“Allah is the Creator of all things" [Quran 39:62]

That He is the Sustainer of all animals, humans and other creatures.

وَمَا مِن دَاۤبَّةࣲ فِی ٱلۡأَرۡضِ إِلَّا عَلَى ٱللَّهِ رِزۡقُهَا

“And no moving (living) creature is there on earth but its provision is due from Allah.“ [Quran 11:6]

And that He is the Possessor of All Dominion and the Controller of the entire universe; He puts whomever He wills in authority and dismisses whomever He wills, He exalts and debases, He is over all things Able. He alternates the night and day, and He gives life and causes death.

“Say (O Muhammad صلى الله عليه وسلم): "O Allâh! Possessor of the kingdom, You give the kingdom to whom You will, and You take the kingdom from whom You will, and You endue with honour whom You will, and You humiliate whom You will. In Your Hand is the good. Verily, You are Able to do all things. You make the night to enter into the day, and You make the day to enter into the night (i.e. increase and decrease in the hours of the night and the day during winter and summer), You bring the living out of the dead, and You bring the dead out of the living. And You give wealth and sustenance to whom You will, without limit (measure or account).“ [Quran 3:26-27]

Tawhid al-Ulūhiyyah (Unity of Godship)

Al-Ulūhiyyah means worship. Therefore, Tawhid-al-Ulūhiyyah means to restrict all actions creatures perform in worship to Allah, the Most High, Alone, such as invocation, oath, sacrifice, hope, fear, reliance, desire, dreading and turning unto in repentance. This category of Tawhid is the theme of the invitation of the Messengers, from the first amongst them till the last.