Source: The Great Interpretation of Dreams (Ibn Sirin)
A nephew (brother's son) in a dream indicates support and backing. Seeing him indicates strength or weakness depending on his state in the dream.
Source: Perfuming Humanity in the Expression of Dreams (Al-Nabulsi)
A nephew (brother's son) indicates a partner or a friend. Seeing him in a good state indicates goodness and benefit.
Source: Signs in the Science of Expressions (Ibn Shaheen)
A nephew (brother's son) is interpreted as goodness and benefit. Whoever sees him happy will attain joy.