Source: The Great Interpretation of Dreams (Ibn Sirin)
Eating coal in a dream indicates consuming unlawful money from a ruler or a dangerous man.
Source: Perfuming Humanity in the Expression of Dreams (Al-Nabulsi)
Eating coal indicates falling into worry or giving false testimony.
Source: Signs in the Science of Expressions (Ibn Shaheen)
Eating coal is interpreted as unlawful money or worry.