Source: The Great Interpretation of Dreams (Ibn Sirin)
Gray hair in a dream is dignity, prestige, and long life. It may indicate poverty and worry. Graying of the beard is better than graying of the head.
Source: Perfuming Humanity in the Expression of Dreams (Al-Nabulsi)
Gray hair indicates weakness of condition or the arrival of an absent person. Plucking it indicates opposing the Sunnah.
Source: Signs in the Science of Expressions (Ibn Shaheen)
Gray hair is interpreted as dignity. Whoever sees his hair has turned gray will gain dignity.