Tawhid - the Science of Unification
Ibn Juzayy says on Tawhid's meaning, in commentary on the ayah of Surah al-Baqarah,"And your God is One God."
Know that people's tawhid of Allah has three degrees:
First, the tawhid of the generality of the Muslims which is that which preserves the person from destruction in the world and saves them from abiding in the Fire in the next life, and it is the refutation of partners and equals, of a female partner and children, and of [other] beings who resemble [Allah], and of opposites.
The second degree is the tawhid of the elect which is that [the person of this degree] sees all actions issuing from Allah alone, witnessing that by means of unveiling, not by means of the reasoning which every Muslim attains. But the station of the elect in tawhid enriches the heart with an imperative knowledge which doesn't need proof. The fruit of this knowledge is the full devotion of attention to Allah, dependence on Him alone, and rejection of people so that he doesn't hope for any but Allah, and fears no-one other than Him, since he sees no doer but Him, and he sees all people in the grasp of overwhelming power, and that none of the matter is in their hands. So he rejects secondary causes and discards [other] lords.
[The person of] the third degree does not seeanything in existence except Allah alone, so that he withdraws from looking at people until it is as if they were non-existent for him. This is what the Sufis call the station of annihilation, which means becoming absent from people until one has become annihilated from one's own self and from one's tawhid, i.e. withdrawing from that with one's absorption in witnessing Allah.