According to the Sufis, the degrees are as follows: First comes tajrīd (spiritual detachment) for the Sufi, then comes the muhakkik (the verifier, one who realizes the truth) for the maʿrifa (experiential knowledge) of unity. After this comes the muqarrab (one brought near). The muqarrab is the one who passes beyond the essence of the essence, and beyond all traces and effects belonging to himself. (Ravza, 606)
Muhakkikūn (plural of muhakkik)... The Sufis have said: The muhakkik is the one whom, while traversing the spiritual stations (maqām), is not prevented by one station from another, nor by one stage from another. The muhakkik is the one who inhabits the stations both in summary and in detail. (Ravza, 619)
The muhakkik is the one who has neither attribute nor essence, and whom nothing in existence can limit. (Kavānīn, 98)