Islamic Interpretation of Dreams (Ibn-i Sirin):
(Blunder; Lies; Tell a lie) Lying in a dream means giving false testimony in court, fabricating a lie, slandering someone, or it could mean constant failure in one’s life. Lying in a dream also means talking nonsense, or letting one’s imagination do the talking, or spreading a sharp idea.
If someone hears that in a dream, and if he spreads the word, then the negative effects of his doing will bring more harm than good.
If one sees himself lying to God Almighty in a dream, it means that he has no brain.
(Also see Blunder)