“אחד” is a reference to Joseph’s G-d. This is made abundantly clear by the balance of the verse, i.e. Pharaoh’s dream is G-D (אחד). Not only does Joseph, unlike the Egyptian ...

What triggers this realization? Joseph says (Genesis 41:25) “Halom Paroh ehad hu, et haElohim oseh higid le-Paroh”. Pharaoh’s dream is one (ehad), that which G-d is doing he has told to Pharaoh.