Tahlīl consists of negation (nafy) and affirmation (isbāt). Its meaning is to declare the Deity as one. The first subtlety is to be saved from manifest shirk (associating partners with God); the second is to be saved from hidden shirk. The third subtlety is to be saved from the shirk of affirmation. Its result is to declare the Deity as one in all existence (wujūd). (Ravza, 305)
(See also: maḥw-isbāt / nafy-isbāt)