If the sons of Yaakov were such great men why did they want to kill their brother?
The sons of Yaakov were all great men.
The Medrash draws a metaphor to a king who wanted to build a beautiful palace. He tried building it on one support pillar and it collapsed. On two, it collapsed and on three it collapsed. When he built it on twelve columns of supports it stood forever.
The Jewish people could not be built on the foundation of Abraham alone. It could not even be built on the strength of our three patriarchs. The Nation of Israel could only stand on twelve pillars of strength. If the House of Israel is to last forever, it could only be built on the strength of twelve sons of Yaakov.
So, if the sons of Yaakov were such great men why did they want to kill their brother?
The Sforno explains that the brothers of Yosef looked at the pattern of history. Their great grandfather Abraham chose Yitzchok to be the progenitor of the Jewish people and he rejected Yishmael. Their grandfather Yitzchok chose Yaakov and rejected Esav. It was only too likely to them that their father Yaakov would choose Yosef and reject them. They had massive evidence that this would happen. The dreams, the multi-colored coat, and the tradition of Shem and Ever that Yaakov passed only on to Yosef.
This rejection, says the Sforno, drove them to formulate an erroneous judgment. It brought them to want to kill their brother.
Didn’t the great sons of Yaakov realize that they were being driven by a biased agenda? The answer is no. Even the greatest, the holiest and the smartest will judge incorrectly if they have an agenda.
We make so many judgments. We reject so many people. We make so many decisions about others that can detrimentally affect their entire lives. Are we qualified?
The first place to look is within us. If we have any agenda, any voice within us that is causing a bias then we are disqualified from judgment.
It took many years until the brothers of Yosef realized that their decision to kill or to sell Yosef was an error. At that point it was too late. Yaakov had suffered, Yosef had suffered and they themselves had suffered.