Rashi cites Chazal, who explain that “b’sodam”, into their conspiracy, is a reference to the incident of Zimri. The tribe of Shimon, following their leader, Zimri, gathered together conspiratorially to Cosbi, the Midyanite princess, before Moshe. Zimri asked, “Is it forbidden to take a non-Jewess as a wife or not? If it is forbidden, who permitted Yisro’s daughter to you?” Yaakov did not want his name involved in this matter. Consequently, when the Torah records Zimri’s lineage, Yaakov’s name is not mentioned, nor regarding Korach. The word “b’kehalam,” with their congregation, is a reference to Korach, a member of the Tribe of Levi, who congregated the entire assembly and rebelled against Moshe and Aharon.
Horav Meir Shapiro, z.l., explains Chazal according to the Talmud in Kiddushin 52b where it is stated, “Happy is he who sees his parents in a superior craft/trade, and woe to him who sees his parents in a mean/defective craft.” He interprets Chazal’s term “craft/trade” as referring to mitzvos and maasim tovim, good deeds. When one is himself involved in the performance of mitzvos, is kind to his fellow man, goes out of his way to help whomever he can, it is appropriate to call to mind the good deeds of his ancestors. After all, he is following in their footsteps, so that the merit of his forebears assists him in continuing on the path of the righteous, of Torah and mitzvah observance. The converse is true when one is involved in an evil craft of sin and mitzvah neglect. For him, it is best that he does not recall his ancestors’ righteous deeds – for two reasons. First, his actions bring disgrace upon them. He has deviated from the path which they have charted for him. Second, the mere fact that he has descended from virtuous and pious Jews is a greater liability. He is held in greater contempt for veering from the spiritual path which his ancestors laid out for him.
Yaakov Avinu, therefore, prayed that his name not be mentioned in relation to his evil grandchildren. Why magnify their sin more than necessary? Emphasizing their origins would only condemn them even more.
In recalling their sin, Yaakov said “For in their rage they killed a man,” and “in their wish they hamstrung an ox.” Chazal say their act of rage refers to executing the people of Shechem for their involvement in, and subsequent indifference to, the violation of their sister Dinah. Yosef is referred to as an ox. Chazal criticize them for their part in the sale of Yosef. Horav Shapiro asserts that Yaakov was rebuking them for their hypocritical behavior. He addresses their anger. Even if we maintain that one could justify their actions — afterall violating an innocent girl is a heinous crime, which deserves a punishment commensurate with the crime — there is still an element of wrongdoing on their part. Shimon and Levi did not attack the people of Shechem out of a sense of righteousness, to punish them for their crime, to rid the world of this virulent strain of evil. They acted in anger! They did not deliberate; they did not have kavanah l’shem mitzvah, religious intent to perform the mitzvah of removing the evil from our midst. No, they acted in anger. Their action was basically negative. Had they thought out their response, there might have been some room to justify it. Their impulsivity rendered their behavior nothing more than revenge motivated by anger and vindictiveness.
Conversely, in regard to their selling of Yosef, had they acted out of anger, there might be some way to vindicate their deed. But they acted deliberately, with premeditation, impervious to Yosef’s entreaties. They knew what they were doing. They did not act out of impulse. They convened a bais-din, court of law, to determine Yosef’s guilt. He was found guilty and deserving of punishment. There was no room for compassion. This was their error. They acted capriciously when they should have been prudent. They were circumspect when a “little anger” would have been appropriate.