Tawḥīd is usually translated “unity” or “unification,” and in ordinary usage it names the central affirmation of Islam. In the Sufi manuals it becomes something more demanding: not a statement to be repeated but a knowledge to be possessed, and one that carries consequences for how the knower can think about himself.
Al-Hujwīrī devotes the second of his eleven veils to it, and begins with a definition that puts the weight on knowing rather than saying:
“Real unification (tawḥíd) consists in asserting the unity of a thing and in having a perfect knowledge of its unity. Inasmuch as God is one, without any sharer in His essence and attributes, without any substitute, without any partner in His actions… their knowledge of unity is called unification.”
He returns to the point to make sure it is not missed: “unification consists in declaring the unity of a thing, and… such a declaration cannot be made without knowledge.” The declaration is not the thing. The knowledge behind it is.
He then divides the term three ways, and the division is worth attention because two of the three are not human acts at all:
“Unification is of three kinds: (1) God’s unification of God, i.e. His knowledge of His unity; (2) God’s unification of His creatures, i.e. His decree that a man shall pronounce Him to be one, and the creation of unification in his heart; (3) men’s unification of God, i.e. their knowledge of the unity of God.”
The middle term does the difficult work. A man's declaration of God's unity is, on this account, itself created in him by God. The unity being declared is not a conclusion he reached.
The definition most often quoted from the tradition is Junayd's, and it is severe:
“Unification is the separation of the eternal from that which was originated in time.”
— Junayd, quoted in Kashf al-Maḥjūb, Chapter XVI
Al-Hujwīrī's gloss makes plain what it rules out: “you must not regard the eternal as a locus of phenomena, or phenomena as a locus of the eternal; and you must know that God is eternal and that you are phenomenal, and that nothing of your genus is connected with Him, and that nothing of His attributes is mingled in you, and that there is no homogeneity between the eternal and the phenomenal.”
This is a guard rail. The Sufi vocabulary of union, annihilation and subsistence — see fanā and baqā — invites the misreading that the seeker somehow merges into God. Junayd's definition forecloses it. What is annihilated is the seeker's attributes, not the distinction between creature and Creator.
Suhrawardī approaches it as a branch of knowledge, and places it first:
“ʿIlm is of three kinds: i. ʿilm-i-tauhid, knowledge of the unity of God. ii. ʿilm-i-maʿrifat, knowledge of the work of God, in respect of annihilation, creation, propinquity (to God), distance (from God), making alive, and putting to death. iii. ʿilm of the orders of the shariʿat.”
Note what this does to the ordering. Knowledge of God's unity is not the summit of a ladder that begins with law and ascends through experience; it is the first of three parallel sciences, and the science of the Law is the third.
Al-Hujwīrī's ordering is itself an argument. Gnosis (maʿrifat) is the first veil to be lifted, unification the second. Knowledge of God comes before the declaration of His unity, because on his account the declaration is empty without it — and everything that follows in the book, from prayer and fasting to audition, is built on those two.
The passages above are quoted from complete public-domain translations, all of which are free to read here in full.
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