Al-Amālī 1, record 231 of the digital edition

Translation

The venerable Shaykh Abu Ja`far Muhammad b. `Ali b. al-Husayn b. Musa b. Babuwayh al-Qummi narrated to us. He said: My father (rh) narrated to us. He said: Sa`d b. `Abdullah narrated to us. He said: Ahmad and `Abdullah, sons of Muhammad b. `Isa, and Muhammad b. al-Hasan narrated to us from al-Hasan b. Mahbub from Muhammad b. al-Qasim al-Nawfali. He said: I said to Abu `Abdillah al-Sadiq (as): A believer sees a dream and it is (i.e. happens, takes place) as he had seen it. And sometimes he sees a dream, but it is nothing (i.e. of no consequence)? So, he said: Surely, when the believer sleeps, there emerges an extended movement from his spirit (i.e. part of the spirit travels), ascending towards the heaven. So, whatever the spirit of the believer sees in the kingdom of the heaven in the place of (Divine) decree and regulation, it is true. And whatever he sees on the earth, then they are confused dreams. So, I said to him: Does the spirit rise towards the heaven? He said: Yes. I said: Until there remains nothing of it in the body? So, he said: No, were all of it to leave until there remained nothing of it, he would certainly be dead. I said: So how does it leave? He said: Surely, you see the sun in the sky in its place and its light and its ray on the earth; similarly, the source of the spirit is in the body and its movement, extended, towards the heaven.

Translation: Bilal Muhammad — published with the edition, reproduced verbatim.