Source: The Great Interpretation of Dreams (Ibn Sirin)
Feces in a dream are money and sustenance. If it is in its usual place, it is lawful money. If it is in an unusual place, it is unlawful money or worry. Whoever defecates on himself has committed a sin.
Source: Perfuming Humanity in the Expression of Dreams (Al-Nabulsi)
Feces indicates relief, the end of worry, and the fulfillment of a need. It indicates money on which zakat (alms) is paid.
Source: Signs in the Science of Expressions (Ibn Shaheen)
Feces is interpreted as money. Whoever sees himself defecating will spend money.