5 Now Joseph had a dream, and when he told it to his brothers they hated him even more. 6 He said to them, “Hear this dream that I have dreamed: 7 Behold, we were binding sheaves in the field, and behold, my sheaf arose and stood upright. And behold, your sheaves gathered around it and bowed down to my sheaf.” 8 His brothers said to him, “Are you indeed to reign over us? Or are you indeed to rule over us?” So they hated him even more for his dreams and for his words.
9 Then he dreamed another dream and told it to his brothers and said, “Behold, I have dreamed another dream. Behold, the sun, the moon, and eleven stars were bowing down to me.” 10 But when he told it to his father and to his brothers, his father rebuked him and said to him, “What is this dream that you have dreamed? Shall I and your mother and your brothers indeed come to bow ourselves to the ground before you?” 11 And his brothers were jealous of him, but his father kept the saying in mind.
Throughout the story of Joseph specifically and the book of Genesis generally we see dreams being one of the main means through which God's revelation comes. Here Joseph has two dreams which imply God's revelation to him. Later we will see other dreams of which God will give Joseph the interpretation. So far in Genesis we have seen Jacob have a dream of a ladder on which angels are ascending and descending from heaven to earth (28:12). Jacob also has a dream in which God reveals to him his blessing and tells him to return to his homeland (31:10). God warns Abimelech, king of Gerar, that Sarah is Abraham's wife, not his sister (20:3). God has also announced to Abraham in a dream that his descendants would one day be in bondage in Egypt (15:13). The author of Genesis has clearly established dreams as a common means by which God communicates to his people.
With all of these dreams of divine revelation in the history of Abraham's descendants, the family of Jacob would have regarded Joseph's dreams with the utmost seriousness. These were not to be taken lightly as is evidenced by their reaction. His brothers are furious and jealous of him indicating they believed the dreams but didn't accept God's choice of Joseph as the one to rule over their family, each of them wishing they were chosen. Jacob's initial reaction indicates he doubts the validity of these dreams, yet because he is a little older and wiser (not to mention his inclination towards Joseph) and has experienced dreams as divine revelation in his own life, doesn't dismiss them out of hand but keeps them in mind.
In the dreams themselves we see a few important details. First, God could be foreshadowing how Joseph would come to rule over his brothers with the imagery of the sheaves. Later we will see Joseph saving the entire region from a famine by storing up grain. In the second dream we see Joseph and his family represented by celestial objects. In the ancient world these celestial objects would connote rule and authority. So in his dream his family is all represented as being rulers as well. This revelation seems to be lost on them as they become jealous even so.
Many pastors and scholars see arrogance in his delivery of the dreams to his family. That may be there, but the text doesn't give us any clues that that is what the author intends. So we shouldn't make too much of it. At best it seems to me to be unwise. At worst it is arrogant. He simply seems to state the details of the dream without rubbing it in. He should have perhaps told his father first and consulted with him about how to proceed. Even so there is little in the text to indicate that Joseph did anything wrong by telling his family. Instead, the obvious fault is in how his family receives the revelation from these dreams.
One of the many fascinating elements of this story is God's timing in giving Joseph these dreams. Why now? Why when Joseph is merely 17 and likely not wise enough to recognize that his brothers already hate him and perhaps telling them these dreams will not go over well. As we see in the rest of chapter 37 it's the delivery of these dreams that pushes his brothers over the edge and causes them to move ahead with their plan to kill him, later changing to sell him as a slave (37:19-20). These dreams given by God are the initial push that set these events into motion.