Jamieson, Fausset and Brown on Genesis 37:5

Ge 37:5-36. The Dreams of Joseph.

5. Joseph dreamed a dream--Dreams in ancient times were much attended to, and hence the dream of Joseph, though but a mere boy, engaged the serious consideration of his family. But this dream was evidently symbolical. The meaning was easily discerned, and, from its being repeated under different emblems, the fulfilment was considered certain (compare Ge 41:32), whence it was that "his brethren envied him, but his father observed the saying" [Ge 37:11].