Source: The Great Interpretation of Dreams (Ibn Sirin)
A brother in a dream indicates sharing in wealth or livelihood. Seeing him indicates strength and severity. His illness indicates weakness, and his death indicates the death of an enemy or health.
Source: Perfuming Humanity in the Expression of Dreams (Al-Nabulsi)
A brother indicates support and help. Seeing him indicates joy and benefit.
Source: Signs in the Science of Expressions (Ibn Shaheen)
A brother is interpreted as a partner or a friend. Whoever sees himself arguing with him will part with his partner.