DREAMS Arabic hulm حلم; nanam ننام; ruya روياه.
The term used for a bad dream is hulm, and for an ordinary dream mauam, ruya being used to express a heavenly vision. [RUYA.]
According to the traditions, the Prophet is related to have said “A good dream is of God’s favor and a bad dream is of the devil; therefore, when any of you dreams a dream which is such as he is leased with, then he must not tell it to any but a beloved friend; and when he dreams a bad dream, then let him seek protection from God both from its evil and from the wickedness of Satan; and let him spit three times over his left shoulder, and not mention the dream to anyone; then, verily, no evil shall come nigh him.” “The truest dream is the one which you have about day-break.” “Good dreams are one of the parts of prophecy.” (Mishket, xxi c iv.)
Based on Hughes, Dictionary of Islam