Praise be to Allaah.
True dreams are a part of Prophethood, as it was reported that the Prophet (peace and blessings of Allaah be upon him) said: “True dreams are one of the forty-six parts of Prophethood.” (al-Bukhaari, 6472; Muslim, 4201)
Dreams marked the onset of Revelation (al-Bukhaari, 3; Muslim, 231).
The truthfulness of the dream is related to the sincerity of the dreamer. Those who have the most truthful dreams are those who are the most truthful in speech. (Muslim, 4200)
Towards the end of time, hardly any dreams will be untrue. The Prophet (peace and blessings of Allaah be upon him) said: “That will be because the Prophethood and its effects will be so far away in time, so the believers will be given some compensation in the form of dreams which will bring them some good news or will help them to be patient and steadfast in their faith.” (al-Bukhaari, 6499; Muslim, 4200)
Dreams are of three types:
(a) rahmaani (those that come from Allaah),
(b) nafsaani (psychological, they come from within a person) and
(c) shaytaani (those that come from the Shaytaan).
The Prophet (peace and blessings of Allaah be upon him) said: “Dreams are of three types: a dream from Allaah, a dream which causes distress and which comes from the Shaytaan, and a dream which comes from what a person thinks about when he is awake, and he sees it when he is asleep.” (al-Bukhaari, 6499; Muslim, 4200)
It was narrated from Abu Hurayrah that the Prophet (peace and blessings of Allaah be upon him) said: “Dreams are of three types: glad tidings from Allaah, what is on a person’s mind, and frightening dreams from the Shaytaan. If any of you sees a dream that he likes, let him tell others of it if he wishes, but if he sees something that he dislikes, he should not tell anyone about it, and he should get up and pray.”
(Saheeh Sunan Ibn Maajah, 3154)
Hope the above listed Ahadees gives you good information on Dreams.
And Allah knows the best.