And it came to pass, when Joseph was come unto his brethren, that they stript Joseph out of his coat, his coat of many colors that was on him; Genesis 37:23
The Eastern text reads: cotina di-pidyatha, “the coat with long sleeves.” These coats or abayas are generally worn by princes, noblemen, and learned men. The sleeves and front parts of the garments are embroidered with silk of diverse colors. Thus, the color is in the embroidery of the garment and not in the material itself. The princes and noblemen never work; therefore, they are attired with a garment with long sleeves. This is a token of honor, dignity, and the position they occupy in society.
On the other hand, a poor man neither can afford a coat with long sleeves, nor can he work while wearing it. Joseph was trained by his father, Jacob, to succeed him as the head of the tribe–in other words, Joseph was elevated to the rank of a crown prince and a scholar. The rightful heir, Reuben, had defiled his father’s bed, committing adultery with one of his concubines. Jacob’s other sons were not intelligent enough to be trained for this high office, the office of the chief of the tribe, which was political, religious, and judicial. It was Jacob who had taught Joseph to interpret dreams and sit in council and manage tribal affairs.
Moreover, the chief of a tribe must find grazing places for the flocks and the cattle of the tribe. He must provide wells, make treaties with the chiefs of other tribes, and lead his people to war if necessary. He must know something about the law, religion, stars, weather, interpretation of dreams, and many other things which are essential to the welfare of a nomad tribe in lands where the people depend on wells for water, migrate by means of the stars, and communicate one with the other through dreams and visions.
Joseph was the only lad among the sons of Jacob who could occupy such an office, so his brothers were jealous of him. All of them except Benjamin were older than he. The very fact that his father had given him such a cloak of honor proved that he had selected him to train him to take his place.
(Lamsa, George M. 1964. Old Testament Light. San Francisco: Harper Collins., pgs 82-83)