The nature of the intermediate life and its subsequent stages have always been subjects of human contemplation. Several Qur'anic verses, such as Al-Mu’minun (23:100-101), Aal-e-Imran (3:169-170), Ya-Sin (36:26-27), Al-Mu’min (40:11, 46), Al-Munafiqun (63:10), and An-Nahl (16:32), explicitly affirm the existence of the Barzakh realm and its characteristics. The eternal life of the martyrs in the path of God and their rewards serve as clear evidence of the Barzakh and its associated blessings. Numerous hadiths—some of which are claimed to be mutawatir (widely transmitted)—discuss the Barzakh realm, the nature of existence within it, reports regarding the states of divine saints, pious individuals, and sinners, as well as the extent and nature of their connection to the worldly realm and the stages of the Barzakh. These narrations are present in the sources of both Sunni and Shi‘a traditions. In lexical terms, Barzakh means a barrier or separator between two entities, a meaning frequently used in the Qur'an, hadith, and philosophical and mystical texts. For example, hesitation in faith has been described as "the Barzakh of faith," an intermediary state between disbelief and belief or between doubt and certainty. Similarly, the period between death and resurrection has been termed Barzakh. From the perspective of the Qur'an and hadith, Barzakh and the grave are synonymous; sometimes, it is referred to as the realm of the grave, and at other times, as the realm of Barzakh. Lexically, Barzakh denotes an entity that acts as a barrier between two things. Accordingly, the world that exists between this life and the Hereafter is called Barzakh, just as in certain Qur'anic verses, Barzakh signifies the division between two seas. In philosophical terminology, Barzakh corresponds to the imaginal world (‘alam al-mithal), as it is the intermediary realm between the intellectual (‘alam al-‘aql) and the material (‘alam al-maddah) worlds. In jurisprudential terminology, Barzakh refers to the interval between death and the Greater Resurrection (Qiyamah Kubra). The Qur'anic verse: "Until, when death comes to one of them, he says: 'My Lord! Send me back, so that I may do righteousness in that which I left behind.' No! It is but a word he speaks. And behind them is a Barzakh until the Day they are resurrected" (Al-Mu’minun 23:99-100). In this verse, Barzakh denotes an unseen realm and one of the stages after death. Based on this noble verse and numerous hadiths that explicitly mention Barzakh, the period from death until the Day of Resurrection is referred to as the "Intermediate World" (‘alam al-Barzakh).
Azadi et al. (Mon,) studied this question.