Source: The Great Interpretation of Dreams (Ibn Sirin)
Lying down in a dream indicates rest and idleness. Lying on the back indicates mastery of the world. Lying on the stomach indicates loss of money and loss.
Source: Perfuming Humanity in the Expression of Dreams (Al-Nabulsi)
Lying down indicates illness or heedlessness. For the fearful, it is security.
Source: Signs in the Science of Expressions (Ibn Shaheen)
Lying down is interpreted as heedlessness. Whoever sees himself lying down is in a state of heedlessness.