Joseph’s brothers hated him because they were jealous. Instead of recognizing that God was at work, they tried to stop his dreams from coming true (37:18–36). These actions show that they were not ready to lead God’s people.
God’s choice of a leader (especially someone young or who seems unqualified) often reveals what is in people’s hearts. It shows whether they are willing to accept that leader’s authority. Joseph’s brothers represent many people throughout history who act with envy (jealous anger) and malice (a desire to harm others) because they are not committed to doing the Lord’s will.
Jacob wondered what the dreams meant because he knew God would choose the next leader. He understood that God could choose the younger son to lead the older ones and could reveal all this in dreams.