What is the fate of the soul during sleep, and how do devils, the evil eye, and envy affect it, and what is the reason for the varying strength of souls among people?

The human mind cannot fully grasp the spirit and its essence, as Allah Almighty says: "And they ask you, [O Muhammad], about the soul. Say, 'The soul is of the affair of my Lord. And mankind has not been given of knowledge except a little.'" The soul is an independent entity that departs the body, experiences bliss and torment, and is neither the body nor a part of it.