Shaykh Al Uthaymeen mentions that from the type of dreams are:
Those dreams which are aided by something which is already established in the legislation thus these dreams benefit strength upon the correctness of that which a person goes towards.
He mentioned:
Ibnul Qayyim mentioned from his shaykh Ibn Taymiyah Rahimahullah: That he saw the Prophet Sallallahu Alaihi Wassallam in his dream. So he asked him regarding things, from that which he asked him was that funerals are brought in front of us and we don’t know whether they are Muslim or Non Muslims. The Prophet Sallallahu alaihi Wassallam said: ‘Upon you is to condition, oh Ahmad’ 
Meaning condition. So say for example: Oh Allah if he is a believer then forgive him, have mercy upon him, grant him ease and respite until the end of the Dua. This dream the legislation bears witness to it.
Explanation Bughul Maraam 2/79
Translated by
Majid Jawed al Alfghaanee