Source: The Great Interpretation of Dreams (Ibn Sirin)
Seeing one's deceased sister in a dream indicates the arrival of an absent person or joy and relief.
Source: Perfuming Humanity in the Expression of Dreams (Al-Nabulsi)
Seeing one's deceased sister alive indicates the end of worry and grief.
Source: Signs in the Science of Expressions (Ibn Shaheen)
Seeing one's deceased sister is interpreted as goodness and joy.