Talbīs is the act of assuming an attribute that is the opposite of one's true nature. (Lumaʿ, 449)
Talbīs: Due to the verse, "We would have plunged them into confusion in their doubt" (al-Anʿām 6:9), it refers to presenting something to creation in a manner contrary to its reality; this is called talbīs. This attribute is muḥāl (impossible) for any other than the Real (God). For Allah, until the time comes to manifest His judgment regarding everyone, He may outwardly show the disbeliever with His bounty as a muʾmin (believer), and the believer with His bounty as a disbeliever.
If one of those belonging to the community of Sufis conceals their praiseworthy virtues with bad traits, it is said that they are practicing talbīs. This term is used only in this sense. Although its root meaning is broader, Sufis do not call hypocrisy (nifāq) or ostentation (riyāʾ) talbīs. For talbīs is used only to preserve boundaries. (Hujwīrī, 474)
Talbīs is to be illuminated by a witness (shāhid, a spiritual testimony) temporarily taken from an existent being. Its first subtlety is the talbīs of the Real (God) to the people of discernment through the cosmos. This talbīs occurs in the connection of the worlds through causes, places, and intermediaries. The second is the talbīs of the people of zeal (gayrat) by concealing (spiritual) moments and by hiding karāma (saintly wonders). The third is the talbīs of the people of steadfastness (tamkīn) by expanding over the world in a manner that also encompasses causes. (Rawḍa, 496)