[Concerning the Punishment of the Grave 1]

Answer—and Allah is the One who grants success: The body is a vessel for the spirit; the spirit is the essence. As for the body without the spirit, it is but inanimate—neither sensing nor feeling pain nor tasting bliss.
On this basis, it is the spirit that experiences bliss or pain.
What supports this is that a sleeper finds, in sleep, terrors and troubles—things he sees and hears and by which he is pained—all while asleep and apart from his waking body and senses; likewise he finds bliss that he enjoys during sleep. In this is an indication that the spirit alone may be punished or enjoy bliss; it can see, hear, perceive, feel pain, be overtaken by joy and delight or worry and grief; it speaks and is spoken to, and so on.
Allah, Exalted is He, says—arguing against the idolaters for their disbelief in Allah and the Last Day: “We will show them Our signs in the horizons and within themselves until it becomes clear to them that it is the truth.” [Fuṣṣilat:53]
Source : Min Thimār al-ʿIlm wa al-Ḥikmah vol.1